I guess it's not an easy question to answer, not many people have fully characterized the behavior of the CIS computer.
But I was looking at the wiring diagram for the circuit I'm interested in:
A thought occurred to me to make a modified MAS relay and power the O2 heater circuit off the fuel pump circuit. The diagram isn't too clear on this but it seems like pin 2 on the MAS relay is a signal (not power) for the fuel pumps to turn on. I could probably remove pin 18 from the CIS computer and connect pin 2 here. This way, the O2 heater circuit is always on if the fuel pump is on.
Edit: Fuel pump gets cut at redline, probably bad idea. Maybe better to use pin 21 as a power source. It's already fused.