Hi MCR, you should have a look at the wiki on the Material System
and it's Blend Modes
. You can blend one texture on top of another, and even animate the textures blended on top.
This means rather than creating a series of textures that are swapped out, you could create a base texture with all black panels. Then you can create a series of textures that are transparent except for the lights and swap these. That way you can have a lot of frames without loading a full 256x256 texture each time.
As an example, check out the /textures_misc/rail_route.png and its rail_route*.tga brothers. In each rail_route*.tga a different stop on the route is overlayed on the base PNG, and in the material definition I'm using, I've set it up to rotate between the TGAs, for an animated sign.
The material definition for that texture is the following:
# Rail Route Board
blend GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
anim 4 0.6
The same principle could be used for your idea, and you can save a lot of space. For instance, all 5 of my 256x256 TGA files (the animation) are less than half the size of the base PNG. So you can have tons of animation sequences to prevent the obvious-ness of the repetition without loading tons of larger files.