you can use a 1" quill stem with a threadless steerer and headset, you just need to find something to hold the headset bearing assembly together.

if you find the right-sized seatpost binder bolt, you can use that around your steer tube to hold the bearing assembly together, taking the place of the (threadless-style) stem, and then insert a quill stem (1" of course). sheldon brown talks about this method somewhere on his website, but i can't find it.