If I understand , I think you are looking how to configure multiple Gatekeeper registaration. Following is the command in the interface mode
h323-gateway voip id name_Primarygw ipaddr x.x.x.x 1718 priority 100
h323-gateway voip id name_Secondarygw ipaddr x.x.x.x 1718 priority 127
name_Primarygw - Primary GW
name_Secondarygw - Secondary GW
x.x.x.x - IP address