Apparently mods for Fallout 3 have been impossible to play on the XBox 360...until now. A user on the XBox Scene forums has managed to figure out to how to do it:
WARNING: Apparently this also requires a modified Xbox 360, so you could get banned from Xbox Live if you do this.
Ok, I'll explain it the best I can. Firstly, I used xexloader to install fallout 3 to an external usb hd from the retail disc. (I already had the expansion packs installed) It would probably work just as well if you installed to the internal hd.
Anywhos... I then connected the hd to my computer where I used xextool to patch the xex to the latest version using the method outlined here.
Then, I edited the fallout3.ini as instructed by the "manual" instructions from this.
Then I took the contents of the mod and put them in their respective places in the fallout 3 directory.
I had noticed earlier that the title update container had an esp file in it so, i figured what the heck? Its a longshot, but ill give it a try. So....
Then, I used this guide to help me make a live container for the mods files. Im not sure what all I needed to put in it, so I just put everything in. The esp file and the folders. Just make sure you fill out the gameid and other stuff for fallout 3. Also, instead of telling it youre making a demo, select the "content" option. When that was all said and done, I had a shiny new live container. I just dropped it into the retail hd with the rest of the expansions.
After getting everything put back together, I loaded up fo3 through xexloader and what do ya know? My little "House Mod" showed up in the downloads list.
The first save I tried was a later save and it took a couple tries to get it to load. It wasnt until I tried an early one that everything seemed to load up and actually work.
Thats it! I hope someone can take this, make some sense of it, clean it up and streamline the process.