As documented in the API page, http_proxy=IP:PORT is used to specify a proxy.

Ideally your organisation uses a transparent proxy where this configuration is not necessary.

In the video above I demonstrate typically how you would configure Webconverger with a proxy server. However a potential problem is if you boot from an install version your proxy might not allow direct access to, meaning you won't get your proxy configuration applied.

In this case you need to hold the Alt or Shift keys to get a boot: prompt to pass the appropriate http_proxy= line, as mentioned on the debug page. Again ideally your network can be configured to always allow access to, so that special network configurations like a proxy server can be retrieved successfully and applied.