Hi Prof
I have built a Magneto switch for my pit and it uses the "-" and "=" commands to activate the mags.
This is the same setup as in CFS1 however you have to assign a keystroke to the magneto command.
So to operate the mag switch you have to first hit the key that you assigned to the mags , this then allows the sim to respond to the increase/decrease selection via the "-" and "=" keys.
Say for instance you choose the "R" key for the mags then the command line would be--
Hit "R" key
then hit "=" key three times to turn both mags on--
then hit and hold the "=" key again until the engine fires. (you must have batt on and full rich, fine pitch etc or motor won;t start)
The "-" key will turn off the mags in the same way or allow you to toggle between them to check for rpm drop--cool hey!
Now this is complicated to replicate these keystrokes into some form of switch for your pit.
I used a two-bit grey code encoder with an auxillary on/off switch and this drives an encoder cct that has two output relays for the "-" and ""=" keys which wire to a bashed keyboard.
The auxillary switch is a momentary switch that operates the "R" key for mag selection.
I have another dpdt switch with a guard cover that is wired to the "=" relay for the starter which I release when the engine starts.
This "-" and "=" function is timed in the sim, that is the selection on the mags times out after a period and the "-" and "=" keys revert back to their normal function. So if you want to use the mags again you have to hit the "R" key again.
I don't know about the fuel tank selection option. Try and assign a key to them and see if it works otherwise you maybe looking at a much more expensive /complicated option with using additional software such as FSUPIC software which will work with CFS2 but NOT with CFS3

Hope this helps. Take a look at my latest pics for a view of the switch. {may have to look for "repost of p51b pics thread )
cheers
chuck