for now hybrid cards on linux are in an experimental stage.
With OSS drivers, using the very latest graphics stack (read X server, DDX drivers, mesa and kernel), you might get it working. If you do, AFAIK it is the best working solution : you should be able to switch redering on the fly. However, using the OSS drivers, you will lose a bit of performance (in case of your radeon, I'm not sure if it's supported yet, check whether it's a SI generation card).
If you decide to use catalyst, catalyst bundles the intel driver, however there is no runtime switching of the rendering card, every time you'll need to restart the X server.
Disclaimer : I have never "production-used" a hybrid graphics system, this is what I gathered from setting up systems for friends and following news.