Follow the directions for a regular installation (routing with local administration, routing with remote administration, or stealth) with these exceptions:
Exception 1 -- When you encounter the Secondary HA Designation window (as was shown in "Installing in Routing Mode With Local Administration"), select Yes, then click Next.
Exception 2 -- When you encounter the Secondary HA Data window:
Type the HA interface. This is the network interface (for example qfe0) on both the primary and secondary systems that are used for administration and HA communication.
Type the HA primary IP address. This is the IP address of the primary machine's HA interface.