@Pappenheimer: Thanks for the answer. The Problem is that i can not use this method in an editor as i do not want to edit mdl files, just for edit the scaling of an object.

I've tried several methods (rotation matrix or e.g. vec_rotate(vec(0,0,1),ent->pan) ==> use vec as factor for z axis scale) but never succeeded.

There MUST be a way. I mean.. other editors get this to, without editing the whole models.