There are some special pliers for this task, but I don't see them as being necessary for the job.
http://www3.towerhobbies.com/cgi-bin...&I=LXVTF4&P=ML
I usually just pop the balls out of the rod ends by grabbing the rod end and it's linkage and leveraging it, till the ball pops free. Or I've always used diaginal side cutting pliers, like a pickle fork, as mentioned above. Another thing I do, although it takes a little more strength and tougher fingers, is to stick a screw through the ball, and then press on the rod end, while the head of the screw rests on a solid surface. With enough force, the ball will pop out of the rod end. The key is to have a screw head that is small enough to fit through the rod end's ball socket area. All methods work, but depending on the ball, it's size, and the type it is (flanged or not), some methods work better then others.