John,
I have done this slightly differently but to the same effect. Using MSDL serial interface cards (which use a standard RS232 output despite what the manual says), and connecting to a terminal server. Telnet to the IP address and port number of the terminal server (create a new port number ie not 23) – this will do the trick. I have done this on a number of occasions but terminal servers can be expensive. This is a good solution if you have a number of switches. ALso if you are call loggin you can use terminal servers for the same purpose.