We had some trouble training our son as well. We did use the potty party method, although we skipped the party part. The important part of all of it was taking some one-on-one time (my husband actually did the training with him, and I took my daughter out with me and left them alone for most of the morning while they did) with one parent, and starting the morning by having lots of little snacks and juices while "training" a doll. We got the "Paul" doll, and the two of them helped "train" the doll, who went from having accidents in the morning to being trained a couple hours later - complete with chocolate frosting poop! LOL!
Then, after Paul was done having accidents, it was time for my son to wear underwear and be DONE with the pull-ups - he's a big boy now! - and with all the snacks and juice he'd been having all morning, he was needing to go potty a lot, so that by early afternoon he was getting it right nearly every time. They were also reading potty books, watching a potty video, and having a very potty-oriented day.
We had a few accidents over the next week, but we followed up with a sticker chart that he'd get stickers on every time he was successful. This went on for a few more weeks - each time he filled a row on the chart, he'd get an inexpensive "prize" for doing well. Then, when he'd finished the chart AND been dry in bed for a week straight, we declared him officially potty-trained and gave him a new set of sheets (he was really into the Cars movie at the time, and so he loved the new sheets) as his final prize.
Overall, it went very well. I recommend getting the book, http://www.amazon.com/Potty-Train-Your-Child-Just/dp/0743... and then adapting the method to suit your own situation. I thought it was terrific that my husband was willing to help with this - It was a great bonding moment for the two of them too!