Redirect a network printer

I have a couple of laptop users at a remote site who connect to the business application via terminal services client. Both laptops share a local printer via the printer port on a router (rather than the LPT1 port of either laptop which may be goneat any point in time). How do I state the Net Use LPT3 command

net use lpt3 \\servername\printer /persistent:yes

to reference the router? Use the IP address of the router?