How do I SFTP over an HTTP proxy with a mac?

I'm not sure that there is a straightforward way to do it with Coda/Transmit and have it "remember" the settings. I use a Mac but I don't really use either of those programs (I just use their bog-standard CLI equivalents, for the most part); I have a sneaking suspicion that tunneling SFTP over HTTP through a proxy is a rare enough situation that it's not going to be built in, but I could be wrong. What I'd do, if I were you, is become more comfortable with the standard commandline methods of setting up a tunnel, and then just use your FTP client of choice to connect to the tunnel endpoint. Or tunnel Skype. Or anything else you want. First thing you'll want to do is install the UNIX program "http://corkscrew.darwinports.com/" via http://corkscrew.darwinports.com/install/. Then you can just follow any of the http://polishlinux.org/apps/ssh-tunneling-to-bypass-corporate-firewalls/ on setting up an SSH tunnel through a proxy firewall. (You'll obviously need a machine outside the firewall to act as your tunnel's endpoint, if you want to tunnel traffic like Skype; your home computer would be the obvious choice.) Basically, you use corkscrew to push through the HTTP proxy, by encapsulating your SSH connection. Then you use the SSH connection to encapsulate whatever else you want to do (by using the -L switch to create a port-forwarding arrangement, or the -D switch to create a SOCKS proxy). Be aware that if you do this, you're probably violating all sorts of well-engineered corporate security policies, since you're effectively defeating the firewall. Think very hard about whether there's a better way of doing what you want, and read the docs for the tools before you use them; depending on where you work, this is fireable stuff you're playing with.