Not the thread I was hoping to find, but a good one:
A lot of it will come down to what is holding the windows in place. Are they bolted or held by some other fastener? If so teh butyl tape may work, but personally I would not use it. If any structural integrity comes from the adhesive (the 4200 that came int eh kit) then you are not going to get them from the butyl tape.
Windos also tend to move, which is a point in favor of butyl tape actually, since it remains goopy forever.