Unfortunately this is a moral grey area for the forums; becuase it's not technically illegal to mod an xbox but the rules do mention hacking/cracking and a definite NO to sharing emulation information.
6) Keep Things Legal
Any discussion, links, or information on hacking, cracking, serial numbers, pirating, warez, or any other illegal matters is not allowed. This includes talks of Emulators and Torrents. The links provide the information needed.
Talks of items that are not yet available by any legal means will also be taken in under this rule. This includes Games, Operating Systems, Service Packs and Betas not released yet to the public. Since there will be no way for people to obtain these by any other means then by Piracy or Warez.
I've modded plenty of xboxes back in the day, similiar to what you're saying. There used to be many active forums dedicated to it. Many have died i'm sure but I don't even remember the names of the ones that were active.
Now they have mini-PCs like the popular Raspberry Pi kit
that are far easier to setup and configure than a modded xbox (don't cost as much either) and have more information readily available for general support, troubleshooting, ect. They also have the added benefit of being legal.
(until you download piracy/emulators/roms/Kodi)