I just finished my annual AED/CPR training on Wednesday this week and I'd say it wouldn't work. First off, an AED is designed to look at the heart's rhythm, evaluate it, and deliver a shock if it's appropriate and at the right time in the rhythm. As Allen mentioned, you don't shock a flat line.
Also, a taser doesn't give one jolt, it's shocks repeatedly for several seconds. While Cheryl's right, you're likely starting from dead, it's unlikely you're going to end up with anything any better than dead in the end. That said, if I was alone in the wilderness and just watched a friend get hit by lighting and they're not breathing and there's no pulse, I'd at least try it since it's the only chance they'd have (I'd also probably try to use my epi-pen, although there's nearly no chance the needle would be long enough to reach the heart muscle).
Contact the American Red Cross. They put one in our office for a very minimal cost to because they're trying to get more of them out there.