Realgen's penis mod and Savestate Furry skins compatibility

[adude1]

Hi, I'm trying to find a way to make the penis models from Realgen's Penis compatible with Savestate's mod which adds some extra skins. Problem is that in the 2nd mod most of the furry skins included and the majority of the custom made ones by other users are not compatible with Simdulgence's models. I understand there's a way to make both mods compatible with each other by editing the skins textures in GIMP and doing something to make the penis texture match.

 

But the main issue is that I have no idea how to do that. Simdulgence did a short guide in the forums long ago but it lacks details and it was for a very old version of his mod (I'm using ver. 2,0), plus he's inactive in Loverslab now so there's no way to ask him questions. 

If anyone here would have the patience to do a guide or step by step instructions to make this possible I'd highly appreciate it. Or if anyone knows any other guide that isn't specifically about these mods and explains texturing for The Sims works too.

Thanks in advance!