Guide to configure FusionPBX with ASTPP

I was wondering if anyone has produced a guide to configure FusionPBX with ASTPP? My providers SIP trunks should be configured within ASTPP as I understand it with all the other configuration set up at the FusionPBX end. External calls would be sent from FusionPBX and would terminate after the call has been routed through ASTPP. Any guide or info would be great to help me understand.
In ASTPP You keep your clients with billing ( call charges and monthly fees for DID's ). SIP device from ASTPP You need to setup as a gateway in Your FusionPBX domain. Then just create a inbound and outbound rules.