The Access Rule List for a specific device can be accessed using the API ACL_GET(nDeviceId), Where nDeviceId corresponds to the ID of the Device whose ACL is to be retrieved.

For reference look at the function, 

static ACL_ACTION fn_NetSim_Firewall(NETSIM_ID nDeviceId, NETSIM_ID interfaceId, NetSim_PACKET* packet, ACL_TYPE type, bool isMAC) which is defined in firewall.c file. This function checks all the rules. In this function, ptrACL acl is the access control list structure and it is defined at the beginning of firewall.c file.