Q: Is it possible to sync together more gameboys by using a 4 way link cable and setting one gameboy to master and then the rest to slave?

A: The 4-way cable doesn't work. But it's possible to sync multiple Game Boys by splitting and splicing regular Game Link cables.

"Master" Gameboy     "Slave" Gameboys (1 or more)

              GND <-> GND
            Clock  -> Clock
       Serial Out  -> Serial In
 
Gameboy link port  no Description Color(Form GBATEK by Martin Korth)
-----------------
  _____________     1 +5V         N/A
 /  5   3   1  \    2 Serial out  Red(orange)
| =###=###=###= |   3 Serial in   Orange(red)
|   6   4   2   |   4 Reserved(SD if it exists) Brown
`---------------'   5 Clock       Green
 (looking at GB)    6 GND         Blue

This is a 6-way LSDJ or nanoloop sync-box i made :

Q: Who made this 6-way LSDJ/Nanoloop sync box and what can I do to purchase one?

A: Was made by Delfy http://www.myspace.com/delfycreations Was custom made for Calbee (and now property of environmental sound collapse), so as far as ordering one goes, you'd have to contact Delfy and see if he'll make another.

Q: Is there a tutorial available for one who knows nothing about splicing gameboy link cables or any cable in general? If not, can anyone make one?