Map serial port through TS

This is a specific Terminal Server set up but a general question for the 2003
server.

I have a workstation which has a cash drawer connected through it's serial
port. The DOS based POS software is installed on the server and locally on
the workstation. It works locally just fine. Ideally the workstation and
users around the cash drawer will connect through the TS from multiple
workstations, make the sale and the software uses a mapped serial port to
send the open command from the TS server through to the workstation which the
cash drawer is connected to.

I cannot get this working. I have been trying to use NET USE and NET SHARE
but so far have got nothing but errors. I have mapped a LTP port using NET
USE just fine. Using the RDP com port mapping does not work if they are not
using the workstation the cash drawer is plugged in to.

The workstations are either thin clients or Windows XP. The server is
running Windows 2003 Server Standard. I found a Microsoft article a few days
ago mentioning that NETBIOS wont work on Windows 2000 but cant find it
anymore and didn't quite think it was important enough.

Any ideas or suggestions would be most welcome.

Tippy.