According to http://www.sidefx.com/docs/houdini/model/attributes you should just be able to set Ce on your geo and have your shader pick that up, but no cigar. Inspection of the Shader reveals the following useful attributes:
- basecolor (this is not Cd of course)
- Cd (as if you didn't know)
- metallic (float)
- transparency (float)
- transcolor (color)
- rough (float)
- aniso (float)
- anisodir (float)
- emitcolor (color)
Note that Cd tints your material. You can't make it emit by going over 1.0 in value.
Then use VEX magic in your geo and have the shader pick it up. You can test with a wrangle and stuff like
v@basecolor = {0,1,0};
@rough = 0.5;