Interfacing an alarm keypad with an arduino

Hi there, I am rather new to the arduino community, and am trying to revive my ademco vista 15p home alarm system with an arduino, as my main panel has failed. Connecting and interfacing the zones sirens and stuff is pretty straight forward, but does anyone know how to interface the keypad? it is an ademco 6150 keypad which seems to have a serial interface, other than that, I am clueless… Please share any ideas you have with me, Thanks!