Steve
Been there; done that <wry grin>.
Enterprise Project Server brings two totally different sets of issues.
Technically: setting up Project Server, establishing and implementing access roles, maintaining the server. This requires understanding of a variety of MS products (SQL Server, IIS, SharePoint, Project Server and, to a much lesser extent, Project Pro).
Organizationally: what benefits are expected, what has to be done with Project Server so that the benefits can be realized, what has to be done to the organization so that the benefits can be realized (this requires substantial investment in determining corporate strategies and looking to see if there is a genuine benefit for the corporation).
It's the last question (organizational change) that's the key. If your organization genuinely believes that few internal changes are needed then your organization needs to do a lot more research.
As for support: two totally different internal groups are affected. The technical side is easily identified. The organizational side needs a top-tier executive as the project sponsor and driver. The benefits of project server are realized at the senior management level. Support is needed to drive the organization and process changes. The changes are such that only those at the most senior levels of the organization can mandate that the new processes *must* be implemented and then adhered to.