Mismatched Port Forwarding On Netgear FVG318?

At work, our proxy blocks everything except for HTTP(S), FTP, and a small handful of other company-specific ports on the _outbound_ connection. On my router, I like to port-forward SSH to my Linux computer server at home but since at work IT blocks out-bound SSH, I have to masquerade the SSH port-forward on my server to get past the corporate proxy. Normally, I've done this in the past by doing something like WAN:9090 (allowed by my IT) --> LAN:22 in my router's port forwards to get SSH routed to my Linux box from the web.

I recently purchased a Netgear FVG318 and it doesn't look like it supports this kind of configuration. In the Security->Firewall Rules->Inbound Rules section of the router configuration I see how to do a port-forward but they only have a drop-down selection of common protocols and will simply 1:1 forward the ports. It doesn't look like it allows to do mis-matched ports on the forward like I'd like to do.