This isn't a shortcut, but an industry "shortcut" you will want to avoid.
Circuit City scams Xbox 360 customers by charging for free service; this from from
Joystiq:
Circuit City is stealing money from those who are dumb enough to give it away. A quick-witted Kotakuite (that's what they call themselves ... ) spotted a poster at a Newport Beach, CA Circuit City. They offer to install backwards compatibility into an Xbox 360 for the low, low price of $28.99.
Backwards compatibility is available through Xbox Live or via a disc you can request from Microsoft. Circuit City brags that "every* game will be backwards compatible." Beware the asterisk (*). The fine print notes that one should "refer to the original Xbox games list to ensure compatibility on the Xbox 360."Riiight.