The conversion of regular Skeletons into members of your army should be possible. Not in to full on Skeleton Warriors, but perhaps an intermediate stage, somewhere between Baby Skeleton and Skeleton Warrior, feature-wise.
They should have an off-hand, and be able to receive augments, but not level up.

As for the method of conversion, that is still up for discussion. My current thoughts on this are that it should be able to be converted much like you would cure a Zombie Villager, and the person who converts it gets to be the owner.