I take it opening Crimson, then selecting the Eyefinity tab along the top isn't working for you? I only ask as mine just displays "A display group could not be created using Quick Setup. Try Advanced Setup instead" but I just assumed that was because my setup is a bit odd.
You should be able to select a game in the Crimson "Gaming" tab, then select the game you want to play in Eyefinity, select Profile Options along the top and turn on "Launch with Eyefinity". The theory (and the demo videos) show you have your system setup for Extended screens, this then activates Eyefinity as soon as the game launches, then goes back to Extended as soon as the game finishes.
For me though, neither of the above work. I click Crimson > Preferences > Radeon Additional Settings to bring up the old CCC interface. From here I can Re-enable or Disable my Eyefinity setup at will to move between merged and separate screens. To make it a bit quicker, I've now pinned the CCC interface to my taskbar, so I just click that and then Enable/Disable Eyefinity setup.