I just read for like the tenth time Bill's fact sheet on callas and I catch the line 'soil should be kept relatively moist' the pot where I potted up my callas don't have dranaige holes on the bottom of them and I've had bad experiences with overwatering and dampning off/root rot. How moist exactly should I be keeping my callas?

Moist, but not sopping wet. Since the pot doesn't have drainage holes, you will probably need to water less often because the excess water has nowhere to go. I would also water sparingly, just enough to moisten the soil.

kennyso,
If possible, drill holes in the bottom of your pot to provide drainage. If that's not possible, putting in a good layer of rocks (1 to 2 inches, depending on how big your pot is) helps keep excess moisture away from your roots. Then, as alankhart says, I would still water sparingly.