Download MotioninJoy then if you have any sony controller laying around or if you have a Xbox 360/Xbox controller laying around then you can just pick it up and play crossfire with it! If you are gonna use a Xbox 360 controller than you will need a Windows Controller Adapter but it's awesome and it's better than using a mouse I use it to play MW2, MW3 BO, WAW etc and it will also work for Crossfire.
I've tried it a long time ago, and it's very hard with Cross Fire. Most console games (or games that use joypads) have an "auto-aim" feature that slows down sensitivity when your crosshair is on someone or it slightly turns the camera towards the person to auto-aim (Call of Duty uses this in all their games for example). So you might think you'll be able to still pro, but the crosshair will seem to move really fast when you try to aim at someone if you are a Call of Duty player or you have played a game that has auto-aim.