A great PMO can not be built from a template. Each PMO is a project. There are many different techniques that can be used. As the PMO manager, you are the cook, architect, conductor for this unique entity. Pick what is best for you. Introduce at the pace that is best for your company.
Many PMO stories begin with some high level executive deciding that a PMO is needed (there are TONs of triggers for this). The exec then selects some poor volunteer from the company and calls in a hired gun - a PROFESSIONAL (read consultant) who knows project management!
The Professional rides into town (cue spaghetti Western music). He has years of experience, comprehensive experience and a goal to make the guy who writes the checks happy. The goal is NOT to create a PMO directly, but to make the pain that the executive is feeling go away. Or at least make it look like it is - this is the "aspirin" solution.
So our hero comes in, interviews executives, holds meetings and Viola out comes a 200 slide PowerPoint that solves everything. Along with this PowerPoint comes a set of manuals that Arnold Schwarzenegger couldn't lift on his best day. The PowerPoint and the manuals are thinly customized versions of the same deck and documentation given to every other customer who needed a PMO.
I know that sounds cynical - but I’ve heard this story too many times. Many times you, the PMO manager, are then left carrying the ball (or hauling the methodology as the case may be). With one small adjustment, you can change this from an unpleasant situation where you are cleaning up the mess to a great starting or changing your PMO. The change is fairly simple.