My little guy is 3 and we're going thru potty-training now. I would allow him to accompany to the bathroom, both my husband and I did, so he could see what was going on when going to the bathroom. We'd often just allow him to sit on his potty when we went to the bathroom, maybe read a book, or talk. I went the Pull-Up route too until it was suggested that I just buy lots of underwear and drop the pull-ups. I did and for awhile there was lots of hand-washing and laundry to be done but he got the hang of it. My little guy treated a pull-up like a diaper and like, your little one, was fine was sitting in the mess all day, without a care in the world. :)
I would also suggest that you allow your little guy to walk around bottom-less for awhile. and then ask him to go with you to the bathroom every 15-30 minutes. Do not ask if he has to go -- the answer is always no, and two minutes later there's a puddle on the floor. Just tell him to keep you company in the bathroom and ask him to have a seat while you sit down.
Much patience and luck to you -- just know he won't go to kindergarten like this :)