Is it possible/advisable to slice deboned Jamon Iberico on a mandoline?
I wouldn't recommend a mandoline for meat because clean slices of meat require a lateral motion with the knife. It wouldn't hurt to try it once just to see (especially after the next recommendation), but I'm pretty sure that your best bet is a sharp knife.

Put the pork in the freezer, still in its packaging, for 20 minutes. That's not long enough to actually freeze the meat, so it won't cause negative effects on the texture, but will temporarily firm it up, making it easier to slice. That works any time you want clean, thin slices of meat.