If you are looking for "red" output, a simple method is to insert a piece of red Roscolux in the fixture. This is a material designed for coloring theatrical lights, is flexible, and can withstand high temperatures.
While this may not be what you are looking for, a modification I did for the bathroom light in my 21 was to add a red LED inside the fixture. It is always on (only draws 10ma) and works well as a night light.
Linear Mode
