If you just need to connect the audio path, you connect the center 2 pins (3 and 4) of the RJ-11 to your audio input on the amp. If you need a relay contact as well, the common is on pin 2, NC (normally closed) contact is pin 1, and NO (normally open) contact is on pin 5. All of this information is in Appendix A of the tech handbook (page 264 of the MCD 6.0 edition).
The AMB page port is programmed as an E&M trunk port, so you'll have to assign a trunk number to it, set a circuit descriptor, and point an ARS Route to it.
So, assuming you just need the audio, take a length of station cable (Cat 3, Cat 5, whatever you have on hand), terminate your blue/white white/blue pair into pins 3-4 of an RJ-11 crimp-on connector, and wire up the other end of the same wires on your amp input.