1) Get corkscrew
2) Add ProxyCommand to your ~/.ssh/config file:
Host * ProxyCommand corkscrew http-proxy.example.com 8080 %h %p
You must change “http-proxy.example.com” with the real proxy address and replacing 8080 with the port on which the proxy listens.
The %h and %p will be replaced automatically by SSH with the actual destination host and port.
3) If the proxy requires authentication, you should change the proxycommand line with:
Host * ProxyCommand corkscrew http-proxy.example.com 8080 %h %p ~/.ssh/proxyauth
The ~/.ssh/proxyauth file contains the proxy user credentials according with the following syntax:
user:pass