We did overcome the major problem where only one user could access non-default trays. The client neglected to mention that the printer was connected by parallel cabel to one PC and shared across the network. Installing the printer as a network device and creating new connections for all users allowed the Word automation code to work properly for all.

I've pretty much given up getting the labels to print to the manual feed tray though. Modifying to the .lbx file didn't seem to work in this case. I've convinced the client that there may be better options anyway. Printing a few at a time from VFP wastes lots of label stock. We will likely accumulate them in a table and print when we have a full page using Word automation where we have better control of the tray destination.

I appreciate your help and the assistance of all others who chipped in to solve the problem.