I think you're asking for the model files. Tremulous models are md3s and don't use bones. If you want to use bones you'll have to make them yourself, use them to animate/pose your model and then output the result without them again.
You can find the models in C:\Program Files\Tremulous\base\data-1.1.0.pk3 (or equivelent). Open the file as a .zip and extract the desired models from the appropriate 'models' directory. They're md3s so you'll need to use a 3D modeller which can open them. If you want to edit the models in another 3D modelling program, open the md3 in something like
mm3d and export to .obj format. From there your desired 3D modelling program should be able to import the .obj and then you can get on with editting it.