I wrote a plugin which creates an orthogonal projectionmatrix.
You can find it here:http://www.coniserver.net/ubbthreads/showflat.php/Cat/0/Number/811731/page/0/fpart/1/vc/1
Just include the dll, call the function to set the materiamatrix to the new viewprojectionmatrix and then transform every vertex with this new matrix instead of 3DGS´ matViewProj in a simple vertexshader.