"Also, what is the proper configuration of the RJ-45 that plugs into the RJ-31X port? 568A?? And, which pair would then land on T1 - R1?"
According to the link I posted, T1 & R1 are pins 1 & 8. These do not match up to any pairs. For 568A they are Green/White and Brown. For 568B they are Orange/White and Brown.
Ring and Tip are pins 4 & 5. They correspond to Blue and Blue/White for both 568A and 568B.
