Image sequence customizing I'm trying to do some scenes which use a mixture of 3D backgrounds with 2D animated characters.The best way I've figured this out so far is to use a plane with an image sequence of pngs which hold the frames.

The problem with this method is Blender seams to only load image sequences based on image numbering. If I wanted to do a sequence which loops say, frames 0-5, then repeats 4-0 for the 'return' of the animation, I would have to load frames doubled up.

Is there a way, maybe with a script, to change the sequence order? I can see it as a useful plugin but my python skills are pretty much non existent.
It is quite easy to do what you want, just learn how to use the Frames, Start Frame**, Offset and Cyclic controls on the Image Sequence node used as the texture of the plane's material. 



Read: Same Video on each face, but with different time delay? 

Then to change to another sequence of repetitions use a mix color node to start the next iteration and animate the Mix Factor



Read: How do you animate image texture materials in blender cycles with keyframes?