hmm I'm not sure an ssh tunnel is ever going to be a practical option for facebook on a mobile...
When I connect to a simple web server I can just open a tunnel with
ssh -L 5000:somesite.com:80 email@example.com
and then go to http://127.0.0.1:5000
in my browser.
That doesn't work on most servers though as they're using virtual hosts so I hack my hosts file with something like:
but that doesn't work with facebook as they're going to have all kinds of fancy load balancers and multiple servers and whatnot.
a quick bit of looking found some instructions for installing foxproxy but I'm not sure this is an option on a phone.
Probably the best option is to setup some kind of vpn as others have suggested.
Actually this does make me wonder if there's a market for a preconfigured sheevaplug or something that could do this.