KarIN: That sounds interesting. You would start at a 20-minute nap, then a 30-minute wake, and then over time increase the time between naps until you got to 3 hours and 40 minutes?
I haven't tried it myself, but I think its success would depend on whether more naps would help the body to adapt more quickly--since 20-minute naps before adaptation after entirely Stage 1 and Stage 2 sleep, you won't get any really high-quality sleep until you adapt (my point being that you shouldn't expect that you won't get tired after a while like every other person who goes polyphasic). But if the increased nap frequency causes you to adapt quicker, then that's just that much less time for oversleeping to rear its ugly head, and that much less time you have to wait before you do reach adaptation.
I'd be interesting in seeing how that method would work--it could well be a far easier transition than what people have done so far. If you decide to try it, please post your experiences here!