I have recently had success with this for my 15 month old. He thought that pu/pd or even just pd/stay in the room was a game. The minute he knew I was leaving/but coming back only if he needed me, things changed instantly.
I put him down, leave, wait outside the door, if he crires the I need you cry I go back in and pd, say night night time, leave, wait outside the door......etc. I only go back in if he needs me. If I just hear the tired cry and he is trying to settle I don't go back in or, if he cries then stops I try to wait 10 sec. to see if he will calm down on his own. I found personally that being in the room until he slept did not work for me - he thought we were playing a game. I also don't see it as CIO because I go back to him if he needs me. At first this took 1 hour and now we are down to 10 min or less for bed and naps. Mine is still in a crib but I think the bed would be the same way, you just keep putting them back in.
I know it's in the Toddler book - I will have a look and see what I can find.