I've set up a source forge project for the software gfx plugin. As i've already said, the goal of this project is to be as close as possible to the real hardware even if it's not possible to play games with it on a slow PC currently. The project isn't very advanced yet, but it's a good start and a good structure to get things easy to understand. I'm currently searching people interested in contributing to this project. If you want to help, or if you want to ask any question, you can contact me on emutalk.
The sourceforge project is there :
http://sourceforge.net/projects/mupen64-gfx
The sourceforge project is there :
http://sourceforge.net/projects/mupen64-gfx