Squad Battles not dead if I can help it!!

[Mowgli]

Is there a guide or tutorial available somewhere how SB map and unit modding works? 

The graphics themselves are just pictures (in bitmap format). You can modify them with any image editing software. The only caveat is that bmp files don't support transparency, so there is no way to have semi-transparent pixels.

So some basic modding is incredibly easy. Anyone is free to edit the graphics to his liking. And in fact, I change almost all my graphics in some way. I just had a rage moment because I was unable to see a very important "high wall" hexside in Afghanistan which cost me the game. I added a shadow so that this can't happen to me any more. More fundamental changes (e.g. concerning the size and display locations of graphics) would require proper modding though.