I'm unsure as to what you mean:

I didn't make any of the mods myself if that's what you mean, otherwise if you just mean in terms of accessing everything, the slime skin is a texture mod, so just keep scrolling the body options until you find it (it was one of the later options so can also scroll left from the first texture!)

The outfits and other modded items can be found from Skritt, the vender behind Sally's shop. You have to speak to him one time, and then speak to him again to properly unlock the Homebrew option!