S.,
I can understand your dilemma. I am also a "non-ferberizer". There are gentler ways to get a toddler to sleep on his own. However, there will be some amount of crying involved, simply because it is not your son's preferred choice of sleeping. In my view, although this is somewhat cry it out, it is not cry it out ALONE.
There are many different ways to do this. 1) you could make a special "nest" for him right next to your bed. When he comes into your room after waking up, you could insist that he lay there. Talk about it during the day when he is happy and awake. Show him the place where he will sleep. Tell him that Mommy needs to sleep too. I believe that is is ok to teach your child that you have needs too. Then when he comes in at night, put him in the nest. He will most likely scream and immediately get up and try to get in your bed. Each time he gets up, put him back down (you may not be able to get him to lay down) and calmly tell him is is time to go to sleep, (my words are Mommy go nite-nite, Daddy go nite-nite, Sister is nitie-nite and son go nite nite.) Don't belabor the process with a long explanation, answering every statement that he says. Just keep putting him down. You may not even have to get out of bed, as long as he doesn't run out of the room. Eventually, if you are consistant, he will get the idea. The first few nights may be rough, but eventually, he will understand. The trick --and the hard part--is consistancy. 2) you could do this same process in your son's bed, with you and your hubby switching off putting him in bed. If it were me, I would stay in the room and plan to camp out for a few nights while he gets used to going back to sleep in his own bed. If your daughter wakes up, maybe you could move your daughter to your bed while you get your son settled in.
Also, if you choose the nest idea next to your bed, you can transistion him to his own room when you move.
Good luck.
Laura