I don't know how to build models at all, and it seems to me that learning would require so much time and efforts
Just use
QME. It's dead easy to use, and it was made for editing Quake models. In a few minutes you can get the job done.
IIRC, using Ctrl+click with the vertex editor allows you to create a new vertex in 3D space. Place the vertexes, create the triangles out of them, put the model flat-posed in a frame called "base", generate the skin vertices from it, paint the skin, create the animation frames, and you're done.