Never really looked at the H2 switches and the illustration in the service manual is not that great.
Now, looking at the H3 schematic, it appears this is not one independent switch but a complete module and all the switches are serviced at the same time.
Normally, this would not be a problem, but it appears the switch that controls the heater element is a two pole switch, not a three pole switch.
In this switch it appears the HI/LO positions are signaled to a heater element relay and to the heater element module with a different resistance signal (similar to cruise control switches).
In basic language, if the module senses 2.5K ohms, it goes into HI, if it senses 4.9K, it goes into LO.
However, it gets more complicated since the relay has a thermistor which is used to control the heat setting, and it appears the module actually pulses the heater element to control the temp.
In addition, the passenger heater element module receives input from the seat belt switch, and unless the seat belt is buckled, there will be no heat. This is probably due to the passenger presence air bag system built into the passenger seat.
Not saying it can't be done, but I would have to ask is it worth all the trouble?
(All this information is based upon the wiring diagrams produced by GM, and there could be some mistakes. I have not actually taken a look at this switch/module assembly, but if I can remember on Monday, I'll see if I can find the module assembly from the yellow H3 that was totally dismanteled...my disclaimer
)