Here it goes.
I have a G2 running Android 2.2.1 with CM 6.1.1
Vending.apk was originally 2.2.6 so I updated it to 2.2.7
Check version by going to Menu/Setting/Application/Manage applications/...
Look under Downloaded if not check under Running for Market. Click on it and check Market version (your version)
I tooked the Vending.apk file from Vending-2.2.7-signed-testkeys.update.zip and replaced it with the Vending.apk from Black_market_3.zip.
You can use 7zip,Winrar or any program that will access these files.
system/app/Vending.apk <- change this file.
Run BlackVending-2.2.7-signed-testkeys.update.zip on ROM Manager
Let you phone reboot check your market and let me know.
just run the update.zip on ROM Manager
All have WORKED.