Quake 3 animations are limited to a set number of frames plus complex animations are hard to make since everything is done per vertex.

It is possible with the Quake3 engine but only on modified Quake3 engines with reenabled MD4 (skeletal) support and reprogrammed MD5 (Doom3/Quake4) models and animation. An example of this is XReal - it is a modified GPL Quake3 engine that can use anything from Quake3 all the way to Quake4 quality of assets. Ofcourse as you all should know, it is illegal to edit WET down to the engine level, only the game code and graphics can be touched.