I would transfer new emulators and roms to your XBOX through
FTP.
Basically:
1) Set up a network between your computer and XBOX. This can be done 1 of 2 ways.
-------a) Connect both to a home network (router, or other means). If your XBOX can already connect to the internet through the same network your computer does, you're all set with this part. However you do need to find your XBOX's IP. I have never used avalanch myself, but there will be a menu in there somewhere that will tell you the IP address of your network.
-------b) Connect an ethernet cable between your XBOX and PC. I have not used avalanch, but you need to manually set an IP address for your XBOX. Find a network settings menu and manually set your IP address to "192.168.0.1" and your subnet mask to "255.255.255.0".
Now go onto your computer, find your "local area network" connection. Right click it and click properties. Then scroll down the list (Windows XP: Probably the bottom of the list, "TCP/IP". Vista: Near the middle of the list "TCP/IP v4"). Double click it. Set your IP to "192.168.0.2" and your subnet mask to "255.255.255.0"
3) Get a FTP program. CuteFTP, FlashFX,
SmartFTP .. all of these will work. Obtain a copy, either illegally or use a 30 day trial.
4) In your FTP program, make a new connection. For the "host", type in the IP address of the XBOX. If you used step 2a, it will be the IP you found. If you used 2b, it will be "192.168.0.1". Port should be 21. Username: xbox Password: xbox
5) Press connect and it should load a list of hard drives (C, D, E, F, G). Open the E drive and look for "emulators". If it's not there, check if there is an "apps" folder and look in there.
6) Upload new emulators and roms
Hope it helps.