Does he have a fav. Stuffed animale? If he does give it to him when its time for bed. And (if he's been sleep with you or where ever) let him sleep there a few more nights with his animale and give it to him durring the day to play with also. If you need any thing else feel free write me.

My son hated his toddler bed the first few night he had to sleep in it.
What the 'professionals' say to do is....
1) introduce the bed with something he enjoys etc. Reading a book or his fav. Bear
2) tell him it's bed time and do what you usually do when he goes to bed.
3) when/if he comes out repeat 'it's bedtime, go to sleep'. If he cries, then let him cry.... All night if you have to (it's hard but it works)
4) if he comes out again don't say anything, just put him back in bed
5) repeat step 4 all night if you have to

after a couple of nights of this, he should adapt to it. Just a suggestion...
Good luck

I whole heartedly agree with michelle. I also had a prem baby and we had the same issues when it came to getting her into her own bed, I think it's due to us over indulging them! anyway this method worked for me, you will have to listen to him screaming for 2 - 3 days and it's awful but it's worth it!