I found this - does it help??
2. Installing Emulaters/content
There are two types of emulators
-God file emulators (Which go within the stock hdd only and show up in the game library in the NXE Dashboard).
-.xex file emulators (Which will not show up in the NXE Dashbourd but can be put in either the stock or external hdd.)
God Emulators
The most popular of these are:
-GenesisPlus360 (Comes in a file called FFED0707)
-SNES360 (Comes in a file called FFED7300)
-MAME360 for retail dash (Stand Up Arcade)
The SNES and Genesis folders need to go in the 360 stock hdd. the hdd can be accessed in the custom Dashboards above (XEXmenu or FreestyleDash). The files go to (Hdd1:/content/0000000000000000/"they go here).
The MAME360 folder will also go in the xbox hdd but in the (content/0000000000000000/CODE0006/00080000/here).
Now they will show up in the NXE Dashboard.
For these two emulators you will put a folder on the root of the external hdd called (_Emus) and whithin this folder you will make a directory called:
-Genesis360/Roms/"roms will go here"
-SNES360/Roms/"roms will go here"
For the MAME360 emulator you will put a folder on the root of the external hdd called (Emus) "no under score".
This will only work if your installing and using it with a external hdd:, also the external hdd must be plugged in the back of the console were the wifi adaptor would go. This will have all the bells n whistles and also a (Roms) folder to put the Mame roms. Once you go into a game with this emulator you must press the left trigger,right trigger and the A button at the same time. This will give you a pop up window with system option. Go into Game Configurations and select wich buttons do what for that games. Thats the Basics on MAME360.
.xex emulaters
The most popular of these are:
-SMS360 (Sega Master Series)
-XeboyAdvance (Gameboy Advance)
The SMS360 and XeboyAdvance emulators have everything you need to run them within the folder except the roms. The folder contains the .xex file,media folder, rom folder (were you put the roms), and a few other folders depending on the emulater.
**Remember the (emulator) folder you made on the root of the external hdd? That is were you stick these type of emulators. Now they will show up in Freestyledash.
sorry - I had to remove a link the guy put in there...