Read the Linux FAQ on HomePNA.org
However, you should know that although you can compile the HomePNA 2.0 (hpna2) module, you won't be able to load the module under Red Hat versions more recent than 7.3.
The hpna 2 module is a closed-source, binary-only module, so there is nothing that you can do about it. Broadcom, the maker of the HomePNA 2.0 chip (all home phoneline vendors use the same chip) refuses to release the source for the module.
I use HomePNA as well. It doesn't compile with kernel 2.6, so I anticipate moving my network to wireless at some point. This situation sucks, I know, but this is exactly why closed-source hardware should be avoided.