IIRC someone (jitspoe?) wrote a command line util that could be used for this. Search the threads in this forum and you'll find the link to download.
The easiest (not the more correct tho) way to fix the problem would be force the .skin field to 0 in ThrowHead(). This way everyone gets the vanilla player head skin when gibbed.
I will check if I still have the generic gibbed head model somewhere in my disks, that would look correct for pretty much any player skin.
Discuss programming in the QuakeC language.