Jon, i usually get my missus to hold the frame level over my work bench then with a block of wood over the cups to protect them i tap them in with a good weighted hammer. i'd use a vice but mine dosn't open far enough, especially on 5" headtubes. with the fork race i gently tap it on with a nylon faced hammer. it's a good idea to put a little bit of grease on your cups before tapping them in. this'll help them slide into the head tube easier.
bear traps are a nice headset and reasonably priced still
