Is it really a telnet server if it requires no password? "All" you need to do is connect the socket, read from it, send a username when it sends you a "login" type text, and away you go. What code have you tried?
I wouldnt advise using Net::Telnet if you want to do actual "Telnet" like stuff, since its options support is quite broken. (Its fine for simple "running commands on telnet servers" though).