Flash custom BIN file with GM Tech 2

I have a Tech 2 clone from china and it's been working quite well as a diagnostic tool. I know these can flash PCM's with stock BIN files from GM to perform updates or for PCM replacement. Word on the street is that you can use a Tech 2 to flash a custom BIN file, but I haven't found much about specifics. Does anyone have any info on this?

You can't really do that, not without a lot of reverse engineering and Tech II protocol hacking. You only can select stock binaries with options using Vehicle Configuration Index (VCI), but no one really knows the VCI codes for that.