Let me preface by saying that I'm no expert! My son is almost 3 and we've been potty-training for the past few months. He's completely transitioned to underwear except for nighttime, and accidents are rare, but do occur (just yesterday, for example!).
We did have trouble with the #2 part. For us, the solution was an *immediate* reward. Our son rarely gets treats (candy) or dessert, so he thinks it is a huge deal when he does get it. We did one m&m for telling us he needs to potty, another one for going #1, or a sucker (dum-dum) for going #2. For some reason, he just loves suckers and thought that was the coolest thing to get! I would even stand in the bathroom and with the cannister of suckers and say, if you go #2 you can pick out a sucker to have! Maybe for your son, candy wouldn't do it, but tiny toys, stickers, calling daddy on the phone... find something that he really does want. (I even considered getting a gumball machine filled with m&m's or something... he would get a penny to use in the machine if he went. We didn't end up needing it, but I think it would have worked.)
In the end, I think it was a combination of the immediate treats, and of him actually being on the potty at the right moment where he actually needed to go #2. We would take him about every hour and a half whether he said he needed to go or not and give him a chance to try, do the whole routine, etc. Eventually, we caught a moment where he just had to go #2, and that helped get the ball rolling. Also, I have to say... this is really gross, but I think it did help... to help him understand *how* to think about going #2, we would tell him to try and toot while he was on the potty. Um, to be honest, I may have even demonstrated the tooting... he thought that was *hilarious* and tried it himself. Sounds crazy, but it did help!
Also, I wanted to add that we made the switch early on from diapers to training pants... the cotton Gerber kind that are like underwear but a little thicker. (Got them at Babies 'R Us and we used the little plastic overlays, too.) We never used Pull-Ups. We made a big deal out of them being special big boy training pants (you could tell him they're like daddy's since the look like underwear). We did use a diaper during naptime and still at night. (Maybe you are already using training pants, though... I couldn't tell from your post.)
Good luck! You're doing the best you can and something will catch on eventually, I promise! As someone at church said to me in the early potty training days, "Don't worry... after all, my son is potty trained!" He's 16! Just reminded me that my son would, in fact, get it eventually!