Handling caramelized onions

Carmelized is basicaly an extraction and reduction of sugar . Therefore it will be sticky and gooy as you describe. The key here  is put them on top of pizza when nthey are still warm. They will come apart easier. Keep in mind pizza cooks at a hi temp and since te onions are already cooked they will tend to cook more and actually become bitter and burn. I would put onions on before the cheese so the cheese can act as an insulater against the hi  dry temp for the onions.

If you add a little oil to the onions (by little, I mean a few drops), after they're done, they'll be easier to work with. And, like chefedb said, put them under the cheese so they won't burn.

I use carmelized onions at work (cold station), and don't have any problem handling them.  Don't slice them too thin and use more oil when sauteing maybe..?

Grumio, you may be cooking the onions down too far.  Yes, they will taste delicous, sweet & creamy gooey sticky all those things at the pan stage.  But, if you're going to cook them further on high temp on the pizza, as Chef Ed says they are going to burn and get bitter. Try taking them off when they are say, 1/2 to 3/4 done,  I like the suggestions of adding the oil to loosen them up in the pan, and also putting them under instead of over the cheese.

For me, I prefer raw very finely sliced red onions straight onto the pizza.  But that's just me :)