Well, this is what I have done in the past and it has always worked...get a box, a little larger around than the litter pan, and about 3-4 feet tall. I usually can go to Wal-Mart, or the refrigerator store and they'll just give you one. Put the litter pan in the box and about every 30 minutes or so, put the kitten in the box and make him stay in it(that's what the high sides are for), watch to see if his uses it, if he does take him out right away, if he doesnt make him stay there for 5 minutes, then take him out. Repeat it all over again in 30 minutes. continue this through out the day on the first day. Then on the second day spread the time out a little longer and so on. This is sort of how you would potty train a puppy, but instead of a box, you would take a puppy outside every 30 minutes. Also, make sure you have an additional litter pan close and ready if he should decide to use it inbetween the 30 minutes on his own.
When you confine a kitten with it's litter box, it has no choice but to use it. Make sure that inbetween times in the big box, you watch him very closely, because if he goes outside the litterbox like on your towel or ect. you'll have to start all over with the process. It tough when a kitten doesnt naturally go in the litter pan, and it takes abit of work to correct this, but it's alot easier than trying to correct this in an adult cat! Dont let it go that far