1) Open all Files
2) Register Stars (normally we would also be normalizing background, rejecting bad data, etc after this part., but for this example we will keep it simple)
3) Close all Files and Open all Blue files
4) Combine All Blue files (sum for small number of images)
5) Save the Sum Combined image as Master Blue
6) Repeat 3-5 with Luminance, Green and Red.
7) Close all files - at this point you should have a Master file for Luminance, Red, Green, and Blue, all of which are already aligned properly.
8) Open all Master Files.
9) Combine files using a color tool:
10) Apply each Master File to the correct color field (Example does not have a Luminance file, just red, green and blue)
11) Create and enjoy your final, color image: