In past operating systems, I have been able to share IRQs for COM ports.

For example, I could have a modem on COM2 using interrupt 3, and also have a serial port on COM4 using interrupt 3.

I couldn't use the modem and COM4 at the same time, but at least they would both work independently and any software trying to access COM4 wouldn't complain about it not being available.

However, I'm unable to get Win2k to play nice with this situation. How do I tell 2k to ignore the fact that these two COMs share an IRQ and that it's OK to let them do it?