Note i did not no were to put this please move if this is wrong section
NOT MINE CREDITS GO TO Dubz Gamerz<a href="http://www.youtube.com/watch?v=Xy-3xAv-6wQ" target="_blank">http://www.youtube.com/watch?v=Xy-3xAv-6wQ</a>
XM360 download link -
http://www.logic-sunrise.com/telecharger-121967-xm360-v18d.html

Put the folder that downloads onto a USB flash drive.
Go onto your retail xbox 360 (non-JTAG) and download the arcade game trials you want to unlock.
copy them to a xbox 360 configured flash drive then transfer the game trials to your hdd on the jtag.
Load up xex and select xm360.xex, Then rescan all it will find the arcade games u have in the game library then simply click Unlock XBLA and there you go! Enjoy