Hello,
I hope the textures will make it soon to a release, I finished the beta version and Carpetsmoker and Stinkmarder are currently trying to make a working mod out of it. I can not say when it is ready, but it must be soon.
If you still want to make some textures, I duplicated the directories which contain the textures (System-m with the modified textures, System-o with the original, I remove the -m/-o to use the one or another ingame). To get the textures into the .u I open the .u's with UEd, import, save and lauch the game. Same procedure with every texture, may it be IMT work or muzzle flashes.
Sadly the same does not work for sounds, you can not import modified sounds into the .u's through UEd
