Personally I think it's a pretty cool idea. You can now get flashing LEDs with integrated electrickery, so you don't need any extra circuit boards or stuff - just a battery and a switch.
http://www.maplin.co.uk/p/3mm-red-led-uk30h
I don't know the details of the kit you want to put this LED into, but in principle you just need to drill a hole where you want the light to go, install a battery and switch in the cavity of the model, and wire it all up.
If you can integrate or adapt the switch so that it looks like part of the hull of the model, so much the better.
Is this link any good to you?
http://www.warseer.com/forums/showthread.php?195182-Lighting-my-Valkyrie