Explicit Proxy with additional ports

Hi,

I'm migrating a firewall to a fg500D with running 5.4. The old firewall contains a proxy too. Beside normal ports (80, 443) there are custom ports like 444, 10777, etc. which are mainly http or https on non standard port numbers.

How can I configure these non standard ports on the explicit proxy in addition to the standard ports?

Any ideas, links to documentation or howtos would be great.

Thanks in advanced.