Here's the link to the thread on XDA where you can get the .exe...if you're using a 6700 all you do is put the .exe on your phone and run it and it'll do ALL the work for you...all you need to do is set up the receiving PC/XBOX to accept the adhoc network...
http://forum.xda-developers.com/showthread.php?t=341398
And for those interested in data usage...the most i've used (i've been doing this for months and play halo3 RELIGIOUSLY during the week, okay probably more like OBSESSIVELY!) in a month is 2.5GB's with my Verizon Unlimited data plan...i RARELY ever use the internet on my phone for anything else though...