"The Usual Places
" will be where you can find the most recent BIOS releases.
I'd set the jumpers on the chip for a 512k BIOS and flash the 1.6 version of X2_5035 to it since that was the last xbox BIOS to be released for Gen 3 modchips.
You can also find a buttload of BIOS files on the Auto Installer Deluxe disc. They're in the Addon packs section.
If you choose this method, you can download & extract AID to your PC. Then use the updater tool in there to add the BIOS addon pack to the ISO before burning to disc.
Now the important question here is: Does your xbox currently work and boot to a hacked dashboard?
If it's in working condition, you can use AID as a boot disc and flash the chip through the AID menu.
Aside from install diagrams, I can't find any other information for this chip online.
Well, I did run into your posts on other forums, but that's about it.