I got the DB9 female to RJ11 cable from MCE today. For anyone who’s interested, here’s the pin out.

RJ11 pin 2 to DB9 pin 3, RJ11 pin 3 to DB9 pin 2, RJ11 pin 5 to DB9 pin 5. Then pins 4, 6, & 8 are jumped together on the 9 pin end.