I want to know whether it is possible to configure LFS to render 3d view with some custom proportions.

There is some option named SCREEN_XMUL and SCREEN_YMUL, but it is not very helpful in my case - it allows to change whole image size, not 3d proportions...

Why do I need it? I have low power laptop (bad graphics, some mobile AMD HD4200) and I want to use lower resolution while keeping proportions of the screen well. I hope you understand.