Yes there is, but it's the most difficult hack possible on the 360.
It will allow you to switch between different BIOS and allow you to select region.
Currently it will only run on consoles with the older kernal, if you have accepted the latest Dashboard updates then currently it will not work on your machine anyway.
There are a few places willing to install the kit but it's not cheap.
If I were you I'd forget it.
If you absolutely MUST play an NTSC game then consider buying a 2nd hand American console.