If you use fc11 that makes things pretty complicated and I'd leave my fingers from it. AFAIK fc11 already uses snapshots of a radeon git-branch (radeon-gem-cs3 I'd guess) in order to enable kms and dri2.
Apparently the new power options haven't made it in that branch, and quite possibly wont until the branch is merged into master again.
So building from git-master right now will most likely give you a not working X-Server... or if you're lucky "just" kms and dri2 will stop working.