How about using Term::VT102? You can use this module as a filter for the escape codes by establishing a callback for the OUTPUT handler.

Also, it looks like the only place Net::Telnet (a base class for Net::Telnet::Cisco) reads from the socket connection is in the _fillbuf method. So you could override that method to filter out the escape codes.

Ideally there would be a way to tell the HP switch that you are a dumb terminal.