ISA - Outbound SSL Over Different Port

By default, ISA only allows outbound SSL over port 443.  To add additional ports you have to run a script.  This script is documented at http://support.microsoft.com/kb/283284.  The ISA firewall service must be restarted for this change.  There are several example scripts available online, but be careful because some of these scripts may restart the firewall service for you.

Networking ISA firewall