No, just the opposite. Try this; extract and open the rakghoul texture you want to use on photoshop, check if it has an alpha channel:
- if it doesn't, give it one and make it a uniform dark gray, the darker it is, the more transparent those areas will be in-game (or metallic shinny if cm_baremetal is allowed)
- if it has one (which is posible, maybe to give it that wet, slimmy shine the rakghouls have), just erase it, replace it with a uniform dark gray as above, afterwards write "cm_baremetal" (no quotation marks) on a note pad or word pad text file, then rename it to file extension .txi and drop it on the override along with the texture with the edited alpha channel.
Then test it to see if it works/does the trick.