The wolfenstein code was released under GPLv3, so if you want to incorporate some Wolfenstein code into Tremulous, Tremulous has to switch to GPLv3 too.
I thought about IQM support in Tremulous, the format is a lot simpler than MD5 and the renderer code for loading / rendering a model should be pretty easy. With the current animation system you could only switch between the poses stored in the file, for control of individual bones you'd need a new cgame api.