In configure mode...
set mgc list <ip_address> [,<ip_address> [,<ip_address> [,<ip_address>]]]
where, the first <ip_address> is the IP address of the primary controller for this G700. If the primary controller is an S8700, this is the IP address of a C-LAN board that is connected to a pair of duplicated S8700s. If the Primary controller is an S8300, this is the IP address of the S8300.
The next three <ip_address> parameters are optional IP addresses of up to three alternate controllers. Each of the three optional controllers can be an S8700 duplicated pair or an S8300 configured as an LSP, depending on the G700's primary controller.
I have my G700's set to..
clan1
clan2
S8300