Boeing 737 NAV Lights

Good question bud

Best I can tell the only way to do it is to map it to a key command or joystick button...

As traches said map it to a key, that's all i do.

I never understood why the stock aircraft on FSX suck so hard. Stupid bugs such as this one, the VC textures are fugly, and they're obnoxiously simplified and dumbed down.

No reason the only part of most people's FSX installations is the gui and the modeling engine 😀

(add-on a/c, atc, textures, etc.)

You can modify your aircraft.cfg file to make the Logo switch control the Nav lights.

The logo switch in the 737 issues a command to turn on a type "9" light. Since there is no true logo light for this model, I use that switch to turn on the nav lights as seen below in my aircraft.cfg file modification:
light.0 = 9, -24.20, -56.60, 3.90, fx_navredm ,
light.1 = 9, -24.20, 56.60, 3.90, fx_navgrem ,
...
light.8 = 9, -29.50, -56.60, 3.70, fx_navwhih ,
light.9 = 9, -29.50, 56.60, 3.70, fx_navwhih ,

Change your default light.x = 3 entries to light.x = 9

If you didn't change anything in the setting under button, then if you just press the L key it turns on all the lights, nav, beacon, position and all others

My previous answer may be confusing to some. Bottom line is just press the letter L key to turn on all lights, and press it again to turn them off, hope that helps all of you.