You are supposed to use a #2 screw extractor. I spent 3 f'ing days trying to get that damn thing out when I rebuilt mine. I ended up drilling a 3/4 inch hole in the side of my case for better access. Still could not get the pin out. I finally gave up. I think the best tool would be a small slide hammer with a hardened screw on the end. I did not have one and I couldn't find one to rent. Snap-On makes one that looks like a decent option, but it was more than I spent on the rest of the rebuild. I just could not afford to spend any more time on it. I tried pliers, screw extractors, reverse drill bits, and nothing would get enough of a purchase on it for me to pull it out. Huge pain in the ass. I called a 4x4 shop around here and the guy told me they don't take them out. Of course, that means you cannot completely rebuild the thing. I think I asked the same question at the time and recieved no help. I know I am not really helping you, though. I ended up sealing up my access hole with a freze plug and epoxy. No problems with it. From what I remember, trying to get at it from the other side was not an option. Good luck.
Edit: If you have the patience and the right drill, you could drill it out and install a new pin. That is hardened steel, so it will be a real bitch.