You don't list what module you're using to help you with this, but I can recommend that you check out Control::CLI. I use it to hop between different machines through the proxy server and get work done.
Comment on Re: Telnet to 1 router through another router
Control::CLI uses Net::Telnet under the hood for telnet connections, so "probably not much, functionally". The code or the comment doesn't obviously indicate what you're using. :)