OK, since there were no responses to this thread I tried it. I made a swage-block and a male punch to produce the hollow base. I had some random 225gr. wadcutters around and tried it out. Pretty quickly I was producing credible HBWCs. Since punching the hollowbase elongated the bullets I decided to seat them partially outside the case like a conventional bullet.
The picture shows the basic tools- the swaging block, the male punch and the punch I use to drive the swaged bullets out of the block.
Naturally there is no load data for these, so after some research and more math than I really like to do I settled on 5.0gr. of Unique as a starting load. I loaded a box of ammo and headed to the range. Overall it worked- a couple of bullets were yawing when the hit the target at seven yards and one full-on keyholed, but the rest flew straight and hit true. The 5.0gr load actually may be too light; I plan to bump it up a little and see if I can't get better skirt expansion. Accuracy was quite adequate when I did my part.