Send emails to Zod and see if you can motivate him. He said he had a whole lot of free time so MWeston sent him a pandora (omap3 device, like the n900) and he "couldn’t be bothered to do anything with it". On the other hand, we could try finding someone else with the brains for it.
I already mentioned a plausible way. Pete Bernert, who created the SoftGPU implementation, had also created open source OpenGL GPU plugin, and OpenGL 2 GPU plugin. http://www.pbernert.com/html/gpu.htm#XGL2 As OpenGL ES 2 supported by N900 PowerVR is a subset of OpenGL 2, it will be fairly trivial to port this code to N900 (both PCSX and PSX4All, which is PCSX derivative). If only we could convince Pete to share the plugin source. Or port it to N900.