Using the following generic aircraft.cfg lights section as a reference,
[LIGHTS]
//Types: 1=beacon, 2=strobe, 3=navigation, 4=cockpit, 5=landing
light.0 = 4, -1.1, 0.00, 1.50, fx_vclight,
The 3 entries after the 4 represent fore/aft , left/right, and up/down coordinates for the effect fx_vclight. It casts a glow without showing the source. Try moving the source around to see what looks good. You can also roam around the effects folder and try other vc lights from other aircraft. I've found several that I think are better than the default pink/red one. Be careful though, I got some that looked just right inside but then from the outside the cockpit and near-by surfaces glowed red!
If it is the 2D panel, open up the panel folder and look for this section:
[Color]
Day=255,255,255 <---overall saturation
Night=225,117,89 <---2D panel face
Luminous=200,200,101 <---2D gauges
with the numbers indicating relative luminosity, 225 max. Look at this section in aircraft that have nice subdued night colors and try copying the values over. Trial and error is needed here. Have fun
