I honestly have no clue hows it done. I have heard they can eat them as well, but I think it would be heavy for their tongue as well as hard to digest. Exoskeletons are easier to digest then bone. Someone may prove me wrong, but since chameleons are mostly insectivorous, I would just stay with the insects. I am thinking that the pinkie mice is a kind of last resort thing, same with eggs, if their normal food is scarce.
With regards to feeding pinkies, i do this once a week with a couple of my large male panthers. I just hold it by the tail wobble it around a bit and zap jobs a gooden.Pinkies have many vits & mins not found in insects ,also with regards to bones and the weight of pinkies.It has been studied by dischner 1958 by using a 100 gram spring balance,he attached food animals to this and let two chamaeleo montium shoot at these, in his papar he states that 43 grams is the maximum pulling power of the tongue but he also states with larger species it must be even more powerful .The pinkies i feed are small(below this weight) and also there bones have not had time to develope fully and ive had no problems with inpaction.Chams are known to feed on fledgling birds(which resemble pinkies) and lizards in the wild. I also have a small breeding colony of common geckos which i also feed to my chams sounds cruel i know but nature is nature