you cannot setup CAC with loop-start sinalling cos the CAC Channel bank does not support ans supervision for FXO
you could try E&m
let me give the circiuts setting for your cisco gateway for Carrier Access
framing esf/sf
linecode bs8z/ami
ds0-group 0 timeslots 1-24 type e&m-immediate-start
choose the right franming & linecode for the CAC
Let me know exactly your solution i could further in setting up your voice card