Now that we're all in the future, I thought I'd give some heads up on a new fix for this gameboy player situation.
I decided to have a another look at raphnet and lo and behold an updated and better adapter cable has been added to the store. It uses a wii plug so it can use a wii classic or even a NES/SNES classic controller! I bought one and I'm so happy that the default "gameboy player" button mapping leaves the select button as the select button =D If you reeeally need the "z" button menu, I found that you can access that easily by having another controller plugged into the second port and using that.
http://www.raphnet-tech.com/produ...