to mod halo reach you will need either a DEVkit or a Jtag, this does not, and never will work on a retail or flashed xbox!
the next thing you need is ascension <download below>
www(.)megaupload.com/?d=C0C8N4BP
and the .map files from your halo reach disc (if you have a jtag im assuming you know how to get the files...)
thats all you need to start!
heres a small tut bellow
making any weapon automatic!
1. Go to the weapon tag and select your weapon.
2. goto trggers and select spew...
thats it...... really simple