Microsoft Virtual PC

Does anybody have any experience in using Virtual PC to run legacy MS-DOS programs? I have a 20 year old controller I need to access that uses an MSDOS editor, which needs to get to the serial port to communicate.
I cannot seem to create a virtual CD to install the add-ons; is this an inherent limitation of DOS under virtual PC? I am using 2004; 2007 purportedly doesn’t have as much support for DOS.