How to inforce an enterprise-wide methodology?

A financial company wants to adopt a global methodology to better master the requirement and design phases of its projects, and to create a manageable enterprise memory. After several studies, the end-up solution is composed of internal best practices in different fields, of RUP and UML methodologies, and of a complex set of products and tools.

Which tactic has been used to spread the enterprise-wide methodology?

For budget reasons, external staff, that represents more than 2 on 3 persons working for this company, receive no more allocated material. Each external person will work on their personal computer.

Internal IT services refuses to install any tool or product on the external staff pc, argumenting that their service scope is only for internals.

After two years of a such experiment, the dissemination within the company is always in phase of initialization. No progress has been seen, and the enterprise-wide methodology is not applied at all, each intervening people uses its own methodology.

Dismaying, isn't it!