It appears that a good choice is, once again -like with pbkit for xbox1-, to use Cg compiler (cgc.exe from free Nvidia SDK 9.5), with profile=vp40 (for .cg vertex shader source) and profile=fp30 (for .cg pixel shader source).
I'm actually trying (not easy) to contribute to the global effort to create a low level assembler that will turn the vp40 or fp30 assembler text output from cg into native NVidia binary micro-code (with the help of the findings coming from Nouveau project). Official NVidia grammar of assembler language could be found. That's a good start.
Once this wonderful tool is made. It will be instantly useful for PC0 platform too.
EDIT: IronPeter is very fast and already released alpha version of assemblers (to use with his ps3rsx library).
Edited by openxdkman, 08 February 2008 - 10:23 AM.