Copy games.dat, genres.dat & publishers.dat to your Vice64X\gamebase directory and overwrite the old files if asked.
Transfer the screenshots to whatever directory on your XBOX you please.
Setup the path to the screenshots in Vice64X.
And of course copy the GB64_v08 games to your XBOX.
That's it.

As of v05 GB64 only supports PNG screenshots, which makes it a little bit trickier to convert them to XBOX compatible format.
GB64_xboxrename.exe (supplied with Vice64X_v07 and newer) only supports GIF images, I therefor had to convert all the PNG's to GIF before converting.
Also manually had to edit the GBC_v05.MDF file in Access to list screenshots as GIF images instead of PNG.
Just a little warning if you choose to convert them yourself.
Kudos to Xport for providing the necessary tools needed (except Access obviously) and of course for bringing us that sweetass emulator called Vice64X.
And last but not least Madmab for the "Madmab treatment".

-Retroplay.