It's really easy. Just keep your wits about you as you work your way around the wheel - half a turn this way, half a turn that way, half a turn this way, half a turn that way - mark where you start, check when you've done one complete 360, adjust as necessary. Then just take the axle out and move the cones along a bit, then reassemble. The whole thing takes no more than half an hour. I could believe how easy it was when I finally took the plunge.
Goos luck!
PS even if you completely screw it up, your LBS will charge no more to retrieve the situation than they would ahve done to do the job - so what've you got to lose?