Hey Neil,
actually it is not that complex. You wrote that you had experience with macros - I assume you have the payed version of FSUIPC.
In order to use the LVARS which are mostly within the document Lewis posted, you need to create a macro file within the modules folder of FSX
I called the file C182_HB-CSN.mcro since it has the 182 comands and the call sign of mine is HB-CSN.
just create a text file and build it like this
[MACROS]
1=L:FSelC182State=SET
2=L:Eng1_CowlFlapsLever=SET
3=L:RadioLightKnob=SET
4=L:PanelLightKnob=SET
5=L:PedestalLightKnob=SET
6=L:GlareshieldLightKnob=SET
7=L:WindowDefrosterControlKnob=SET
8=L:AnnunciatorPanelTestSwitch=SET
9=L:FloodLight1Switch=TOG
10=L:FloodLight2Switch=TOG
11=L:StaticAir=SET
12=L:GpsNavSelector=SET
so it starts with [MACROS] and is sequentially numbered. Depending on the comand there are options (seen in the document mentioned earlier, also the FSUIPC docu is really well written).
So comands 8 & 12 are relevant for you. You could leave out all the other stuff and number them 1 & 2, or whatever, just no duplicates are allowed.
After the file has been saved, go to your FSX and open a flight with the desired airplane.
Within FSUIPC go to Buttons & Switches, [IMPORTANT] click to "Reload all buttons" and flick/click whatever you want to assign to and then find within the comand list on the right the values/entries from the macro. The last thing is to assign on the various button presses the right comands. I have a spring loaded two way swith for the Annunciator (best I could get) and when holding to TEST, it is in test mode, when going into NIGHT position, it is staying there. When I want to go back, have to go to TEST and release.
To make it easier for you, I made screenshots but not to make it too easy, they are from the 172 configuration but very similar except the name of the macro-comand.
for holding button up:
and going into night mode:
Final result here:
see my custom build switch panel on the bottom left.
One remark to the MACROS - I still haven't figured the FloodLightSwitches - any hints welcome.
And last, the GpsNavSelector changes its state on press. meaning you set it to 1 and it switches to the other value. I don't think that it can be set directly to GPS or NAV, it cycles.
Hope this was of any help
Cheers,
SJ
PS: if anyone is interessted in the switch panel, ask me for details and I am happy to share.