So I got the Xbox remote control working with MythTV.
Thanks to the Gentoo project for including the patches in portage to make it easy.
If you're following along, here's how I got it. Get the LIRC package, and tell it to compile the xbox driver.
LIRC_OPTS="--with-driver=xboxusb" emerge =app-misc/lirc-0.7.0-r1
Note that if you have an unofficial receiver you may need to patch the driver to include the USB vendor and product IDs of your device, which can be discovered by doing a lsusb.
Now plug in the receiver, it should get detected, check with dmesg. Now copy the xbox lircd.conf that Gentoo provides.
cp /usr/portage/app-misc/lirc/files/xbox.lircd.conf /etc/lircd.conf
Now start lirc and test it with irw.
Assuming that all works, make lirc start automatically.
rc-update add lircd default
Now I set the remote for MythTV by making a lircrc file. Follow the instructions in the irxevent man page and the MythTV docs.
I also set up the computer to autologin to the tv account now and it's great, working well. Thumbs up to this remote control combination.