Ok. What was your question?
Seriously, I have a demo program that illustrates how to do this without specific cube mapping hardware. I’ll probably put that demo on my web page in a day or two, but you should use EXT_texture_cube_map if you have hardware that supports it. Even if you don’t, you should probably use dual paraboloid or sphere mapping if you don’t have cube map support.
My demo is intended to help people understand what cube mapping looks like without requiring they buy cube mapping hardware. It takes 6 multitextured passes, and is really not a viable technique for general-purpose environment mapping.
Hope that helps -