Till this summer, I had routinely just ridden with presta tubes in Schraeder-valve rims, w/o problems. This summer I broke down and bought a new pump head (Silca), which actually grips the valve, and pulled out two valves while removing the pump head. For us bottom-feeders, this is almost major, and we certainly aren't going to either use Schraeders or abandon the rims. I have found that some RadioShack rubber grommets designed to keep wires from fraying their insulation when they pass through metal chassis work fine as adapters. Little tight setting, but some "303" rubber protector from REI did fine to lube the rubber - and the tube for first insertion. This is hardly original with me, but I'll call it "research" instead of "plagiarism" since I've taken ideas from lots of people instead of just one... Maybe it will help you. Maybe you have found a better way; love to hear about it.
harvey sachs
mcLean va