IRC via proxy with password

some IRC clients honour exported environment variables, e.g. Polari works even with a passworded proxy.

export  http_proxy=http://USERNAME:PASSOWRD@proxy-server.example.com:3128/
polari
unset   http_proxy  
# unset removes the proxy redirection Bash variable for direct connection

will work with the IP hidden by the proxy.

Open proxies without password are easier to use, e.g. KDE system-settings allow for a system-wide proxy, just a password cannot be set.