You could wire a 12 VDC source direct to the heating elements with an in-line switch, but I would not recommend it.
The switches in the console do not supply power to the elements, they merely signal the seat heater control module what setting has been selected. If you bypass the seat heater control module you will lose two important safety features. There is a thermistor in the seat that tells the control module if the seat temperature is too high, which shuts off power. There is also a link from the body control module to the heater control module that cyles the seat heaters on and off if vehicle power is low, and shuts the seat heaters off when vehicle power drops below a certain point.
Seat heating systems are designed to bring the seating surface up to temperature in a very short period of time. I would leave it set up as is.
2001 Bonneville SSEi (retired at 365,000 Kms.)
2014 Jeep Grand Cherokee Overland (yes, I know its not a GM)