question.. what the hell makes you think that you want a static source port for ssh? Do you realize the potential pitfalls that will cause for other applications that use dynamic source ports? I assure you is quite normal to use dynamic source ports.
The answer which has been stated twice already is this: forward ssh to your ssh server, and keep state on the pass rule. If your firewall does not do stateful inspection, or does not maintain state, open the port blindly and use tcpwrappers or something in /etc/ssh/sshd_config to restrict access.
Passing flags S/SA will allow the SYN packet to get through and keeping state on the connection will allow the sshd to respond to the clients request and let the connection continue..until said connection is established..and it will keep the session alive until it expires or the connection is closed. The rest should be transparent.

**cleanse senior member gene pool**
-hog