Yes, I agree that enhanced cooperation may be the way forward. However, for clarity first all the member states should proceed with ratification of Lisbon. The only countries where this is at risk of failing are the UK (the House of Lords debates it tomorrow) and the Czech Republic (no date set for either chamber of the parliament, pending a Constitutional challenge).

Once you have 24+ countries who have agreed to Lisbon you have the political capital to attempt to establish enhanced cooperations in all the areas covered by the Treaty of Lisbon.

Also, even if a veto is given on an enhanced cooperation requiring unanimity, nothing prevents the concerned states from agreeing their own treaty outside EU structures as long as the treaty doesn't hinder the EU (which member states cannot do according to the Treaties). This was the way the Schengen area started: France, Germany and the BeNeLux relaxed internal border controls by a separate agreement, and since this didn't hinder but assisted the functioning of the Common Market there could be no objection from the EU. Eventually this "outside treaty" can become the basis for an "enhanced cooperation" and then for a new EU Treaty.

Note one important feature of enhanced cooperations: every member state can take part in Council deliberations on it, but only the member states forming the cooperation can vote. Also, I believe it is possible for a country to vote in favour of an enhanced cooperation but not actually take active part in it.

The rules for Enhanced Cooperations post-Nice appear in the Consolidated Treaty establishing the European Community

Article 11

1. Member States which intend to establish enhanced cooperation between themselves in one of the areas referred to in this Treaty shall address a request to the Commission, which may submit a proposal to the Council to that effect. In the event of the Commission not submitting a proposal, it shall inform the Member States concerned of the reasons for not doing so.
   
2. Authorisation to establish enhanced cooperation as referred to in paragraph 1 shall be granted, in compliance with Articles 43 to 45 of the Treaty on European Union, by the Council, acting by a qualified majority on a proposal from the Commission and after consulting the European Parliament. When enhanced cooperation relates to an area covered by the procedure referred to in Article 251 of this Treaty, the assent of the European Parliament shall be required.
   

A member of the Council may request that the matter be referred to the European Council. After that matter has been raised before the European Council, the Council may act in accordance with the first subparagraph of this paragraph.
3. The acts and decisions necessary for the implementation of enhanced cooperation activities shall be subject to all the relevant provisions of this Treaty, save as otherwise provided in this Article and in Articles 43 to 45 of the Treaty on European Union.

Article 11a
Any Member State which wishes to participate in enhanced cooperation established in accordance with Article 11 shall notify its intention to the Council and to the Commission, which shall give an opinion to the Council within three months of the date of receipt of that notification. Within four months of the date of receipt of that notification, the Commission shall take a decision on it, and on such specific arrangements as it may deem necessary.

Articles 43-45 refer to "freedom of establishment" - that is, enhance cooperation can't curtail it; article 251 describes the codecision procedure.

Enhanced Cooperation is developed further in the Consolidated Treaty on European Union, first in relation to the Common Foreign and Security Policy:

Article 27a

1. Enhanced cooperation in any of the areas referred to in this title shall be aimed at safeguarding the values and serving the interests of the Union as a whole by asserting its identity as a coherent force on the international scene. It shall respect:
-- the principles, objectives, general guidelines and consistency of the common foreign and security policy and the decisions taken within the framework of that policy,
-- the powers of the European Community, and
-- consistency between all the Union's policies and its external activities.
2. Articles 11 to 27 and Articles 27b to 28 shall apply to the enhanced cooperation provided for in this article, save as otherwise provided in Article 27c and Articles 43 to 45.

Article 27b

Enhanced cooperation pursuant to this title shall relate to implementation of a joint action or a common position. It shall not relate to matters having military or defence implications.

Article 27c

Member States which intend to establish enhanced cooperation between themselves under Article 27b shall address a request to the Council to that effect.

The request shall be forwarded to the Commission and, for information, to the European Parliament. The Commission shall give its opinion particularly on whether the enhanced cooperation proposed is consistent with Union policies. Authorisation shall be granted by the Council, acting in accordance with
the second and third subparagraphs of Article 23(2) and in compliance with Articles 43 to 45.

Article 27d
Without prejudice to the powers of the Presidency and of the Commission, the Secretary-General of the Council, High Representative for the common foreign and security policy, shall in particular ensure that the European Parliament and all members of the Council are kept fully informed of the implementation of enhanced cooperation in the field of the common foreign and security policy.

Article 27e

Any Member State which wishes to participate in enhanced cooperation established in accordance with Article 27c shall notify its intention to the Council and inform the Commission. The Commission shall give an opinion to the Council within three months of the date of receipt of that notification. Within four months of the date of receipt of that notification, the Council shall take a decision on the request and on such specific arrangements as it may deem necessary. The decision shall be deemed to be taken unless the Council, acting by a qualified majority within the same period, decides to hold it in abeyance; in that case, the Council shall state the reasons for its decision and set a deadline for re-examining it.

For the purposes of this Article, the Council shall act by a qualified majority. The qualified majority shall be defined as the same proportion of the weighted votes and the same proportion of the number of the members of the Council concerned as those laid down in the third subparagraph of Article 23(2).

There are similar provisions for enhanced cooperation in "Police and Judicial Cooperation in Criminal Matters" (Article 40), and the entire "Title VII" (Articles 43-45) details how enhanced cooperations are supposed to work.

When the capital development of a country becomes a by-product of the activities of a casino, the job is likely to be ill-done. — John M. Keynes

You assume Ireland would want to veto it.

There are even more parts of the Lisbon Treaty which can be implemented easily using the Nice Treaty: Let me cite here Article 4 from the Protocol on the Enlargement of the European Union (I found this on Jon Worths Euroblog):

2. When the Union consists of 27 Member States, Article 213(1) of the Treaty establishing the European Community and Article 126(1) of the Treaty establishing the European Atomic Energy Community shall be replaced by the following:
`1. The Members of the Commission shall be chosen on the grounds of their general competence and their independence shall be beyond doubt.
The number of Members of the Commission shall be less than the number of Member States. The Members of the Commission shall be chosen according to a rotation system based on the principle of equality, the implementing arrangements for which shall be adopted by the Council, acting unanimously.
The number of Members of the Commission shall be set by the Council, acting unanimously.'
This amendment shall apply as from the date on which the first Commission following the date of accession of the 27th Member State of the Union takes up its duties.

This means that the decrease of the number of Commissioners is already implemented.