@hobanagerik getting there! I finally had some time to think. In addition to enabling LVARs I had to install the MSFS LVAR bridge manually. I have now sucsessfully set the fuel pump as per your instruction 
I changed the button config to on/off, but I guess I did not have to do that to make it work.
question 1:
Is it possible to force the switch in the virtual cockpit to mirror the physical switch when using SPAD/Lvars?? I have used the in-sim assignements for the on/off switches for the lights, and then it is impossible to turn the lights off using the mouse, if it is set to “on” on my yoke. it simply wont move. Is this behaviour possible in spad for the fuel pump?
question # 2: I have tried to identify the right LVAR for the alternate air switch, but I could not identify it in the data monitor. Suggestions for that one?
again, many many thanks