Yes it is possible and the good news is you only need one Ati card to be able to use Eyefinity 3. Since I'm an Nvidia user, I can't be of much help.
You can check AMD's website on how to setup eyefinity plus there's dozens of videos on youtube. Anyway the most important thing is that your video card have at least one native DisplayPort.
Perhaps you can list out the hardware you currently have and plan to get so others can get a better idea to help you out?
"Believe me! The secret of reaping the greatest fruitfulness and the greatest enjoyment from life is to live dangerously!"
Friedrich Wilhelm Nietzsche