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.