Changing the animated billboards

Hi, first post here. :D

I would like to create some new content for the animated billboards. I've looked through the 'Modding the game' sticky, so am able to access the raw files, but can't figure out the ones I need to check for the animated boards. Can anyone offer some pointers to get me started? :)

Thanks FWH for this crazy game! :cool:

Changing the animated billboards