Crawls out from under his car, covered in grease
I haven't used the tool in years, but here's what I remember after re-reading the instructions:
Take the tool apart. This means removing the 'expander' (the part with the black rubber rings) and unscrewing the center bolt completely.
Install the BLACK tube into the "cap'. (This presumes you're using it on a Ford transmission, of course) Remove the allen head screw to get the tube in far enough, and reinstall the screw to lock the tube in place.
Put the new bushing on the 'expander' and slide the 'expander' over the black tube. Rotate the expander so it locks in the 'cap'.
The black tube should fit over the output shaft and line up the bushing correctly. Use a plastic or rubber mallet to hit the back of the cap, and the bushing should start going in. The tool will bottom out once the bushing is in all the way.
If any part isn't clear, let me know.