Although I have never done it, you can boot anaconda from grub and I wonder if you couldn't put a ks= as parameter in the grub conf? Setting up software raid in ks is easy. You can also install via url with ks.
I just did this and it works. A complete grub stanza booted and installed via url with a ks file completely non interactively without a dhcp/tftp server or cd.
"Works For Me" (tm) Heh, jlc