After reading that, it suddenly clicked that this could easily be done for MXS, but MXS textures can then be laid over the top of that. Here's what I did:
1) Made a base colour texture, made the decal the size of the map
2) Made an overlay texture like in that tutorial, and made a program that wrote the decals out so they tiled.
3) Put regular decals over the top (the track part)

So, tell us what you think about this system. Do you think it is the way to go? I would probably keep the on track textures the way they are, but use the MVA method for off track, as its more variant.
If it gets interest, I'll make up a new blank track folder.
Mind you, the overlay tile in this was only quickly done.
Try it out (called Hybrid Texture Test in game). Please refrain from using anything here till I release something official:
http://www.2shared.com/file/5578409/205 ... etest.html