There are some threads on this. I started one awhile back that got lots of replies. I made my own headset press awhile back for $15 at a hardware store - long bolt, brass bushings (need to get correct size to fit 1" or 1.125" headset cups", large washers and a nut. You just tighten the nut and it forces the headset cups in like a knife into butter.

The trickier part is tooling to get the headset cups *out* of the frame in the first place.