here are the details
http://docs.blackberry.com/en/admin/...e&subCategory=
in nutshell do following
stop services on both server
backup your database,
Did I mention backup your database? yes pls do it
install update on primary server
reboot and test the functionality,
if your update fails, Keep the services stopped and un-install the update and restore your database then restart services
if all ok then go ahead with applying update to standby server and reboot that box too
test failover and failback