it's been a while since this was posted but I decided to DIY one of these cables before I discovered alignmaster due to limited available stars for a PA.
I figure I'll still so this just to keep the HC up to date anyway.
Point is, I believe a 6 pin rj11 is actually designated as an rj12 plug.
rj11s are 4 pin and rj12s are the 6 pin equivalent.
Just in case anyone is following this write up (excellent by the way) and grabs a bunch of rj11s and cant make 6 go into 4
