I think you're asking about USOC RJ45S, which has nothing to do with
network wiring. I've never seen a true one in the wild, but they
were used for data hookups, apparently.
Perhaps this will help:
http://www.suttleonline.com/pdfs/misc/USOC_Guide.pdf
and a bit more on programming resistor values:
http://www.shout.net/~wildixon/telecom/rj/68_502.html
--Chuck