Take a look in your evox.ini and figure out what directory the "autoadd" command is pointing to for games. Then just use boXplorer to create a new folder in this directory and copy all of the contents of D into this folder. Reboot your Xbox and you should see a new listing in your EvoX game launch menu.
As far as the size of the game... I don't know for sure, but I'm guessing it is similiar to a PC when you ask it the size of a CD-ROM... 6.7 Gb is probably the size of the entire DVD-ROM media, not what is actualy used. Take a look around these forums for the size of some common games, I know most games are much less then 6.7Gb