Wasn't familiar with the construction of those mods. The pic you posted, that's aluminum and it "is" the wire, the board is grounded to that part of the case through the charging board I believe, I can't see a wire at hole #6 although it could possible be on the other side. So no wire needed for the NEG battery post or the NEG atty connection.
It's Sunday. but I'm sure someone more knowledgeable will chime in soon.