Here are the steps to tunnel SSH through http-proxy server. This requires no server-side modifications.

1. Build corkscrew.

Download the updated corkscrew repository here.

Unpack and build corkscrew:

    $ tar -xzvf corkscrew.tar.gz
    $ cd corkscrew  
    $ ./configure
    $ make install

Verify installation:

    $ which corkscrew
    /usr/bin/corkscrew

2. ProxyCommand in SSH Config File

Add ProxyCommand in your SSH config file. It should look similar to this:

   Host aws-host
      Hostname ec2-11-111-111-111.ap-southeast-1.compute.amazonaws.com
      Port 22
      User ec2-user
      IdentityFile key.pem
      ProxyCommand /usr/bin/corkscrew _http.proxy.example.com_ 8080 %h %p

3. Verify connection to SSH

Verify connection:

    $ ssh aws-host