Corkscrew is a tool for tunneling SSH through HTTP proxies. Setting
up Corkscrew with SSH/OpenSSH is very simple. Adding the following
line to your ~/.ssh/config file will usually do the trick (replace
proxy.example.com and 8080 with correct values):

ProxyCommand /usr/bin/corkscrew proxy.example.com 8080 %h %p

Basic HTTP authentication is also supported, you will need to create a
file that contains your usename and password in the form of:

username:password

I suggest you place this file in your ~/.ssh directory.
After creating this file you will need to ensure that the proper perms
are set so nobody else can get your username and password by reading
this file. So do this:

chmod 600 ~/.ssh/myauth

Now you will have to change the ProxyCommand line in your ~/.ssh/config
file. Here's an example:

ProxyCommand /usr/bin/corkscrew proxy.work.com 80 %h %p ~/.ssh/myauth

The proxy authentication feature is very new and has not been tested
extensively so your mileage may vary.