An on-line slow draft does work very well, though it can be frustrating. Especially when it first gets underway... there can be a flurry of picks in the first few hours, and then the guy with the 7th pick takes almost the full 12 or 24 hour limit. Drives people crazy. But that's why you give yourself time to get it done. I'd say, just to be on the safe side, give yourself a day for every 10 picks. For example if you have 5 rounds of 10 picks each, don't have the draft on March 31st.
E-mailing or texting the next guy after you pick is helpful. Another thing to do is to leave a list with the comish. Say you're going to bed, you're on deck to pick and you know you'll be too busy to check in the morning. You can "authorize" the comish or another manager to pick for you. All you have to do is PM him a list of two names - your first and second choice, since if there's only 1 pick in front of you, you're guaranteed to get one of them. I hesitate to do this myself, as I'm kind of obsessive about keeping my draft strategy to myself, but if you know you're going to be away from the computer for awhile, it can really keep things moving.