If your character can cast first level wizard spells, or can talk your party wizard into giving you a hand, Unseen Servant could load your X-bows for you on the cheap. But, for color, I think making your X-bows partly from bone and then casting animate dead on them (creating undead weapons) would be cool - not legal, but cool (and, thus, probably allowable by the GM).
*flaps in and steals undead crossbow* I am the terror that flaps in the night! I am the mammal that lays eggs! *flies headfirst into telephone pole*