You can install it on both of them and they will both reboot.
Do you know of a KB or steps guide to patch an HA pair without CC..
You will find it in the product guide.
Upgrade a standalone firewall or HA cluster
Use the Admin Console to upgrade a standalone firewall or HA cluster with these high-level steps.
To upgrade an HA cluster, upgrade the secondary/standby firewall first, then upgrade the primary firewall. Once both cluster members are upgraded, the policy synchronizes.
1 Create a configuration backup.
2 Download the package.
3 Install the package.