Thanks, all. I have all of the instructions gathered, including the PDF of the TSB for the revised remote opening from 10 April 1998 (when the fob and key were incorporated into one unit.) So, it seems that there are three processes:
1. Key cutting.
2. Key/transponder programming.
3. Key/remote opening programming.
Phew! The helpful Lexus dealer, although charging an arm and a leg, is looking like a plan.