I've done it before. It's actually quite easy. As ImThatGuy said, a flat tip screwdriver (I always put some electrical tape on the tip to protect everything against scratches/gouges) and some pliers will get the job done. You just have to rotate the engine so the base circle of the cam is on the follower and then pop it out.
Awesome. I've done the large screw driver trick myself, but only on the front cylinders. I was worried there wouldn't be any room for leverage up towards the firewall.