So I was intended to do a PRT implementation in my engine, I got most of it done. but then I ran into a few issues

I based all of my techniques off of this article http://www.cg.tuwien.ac.at/~tivolo/Bachelors%20Thesis%20-%20Precomputed%20Radiance%20Transfer.pdf
(I am referencing part 4.3)

The question is, how do I render light coefficients to a GBuffer? Do I render a cube map as an actual cube, and then project the textures? Or am I over complicating everything?
BTW: I learn best from example