LaserJet 8000DN: net use LPT1 does not print correctly

I have been working with a LaserJet 8000DN, trying to get it set up to work
with a DOS application for a client. This is an accounting type of
application that prints checks. They wanted it set up so that when they print
checks it will print from Tray 1 and when printing from anything else it will
go the large capacity Tray 4. The printer is set to Tray 1 = First, and the
rest of the trays are default to Plain. I am using two different drivers. The
driver I am using to print to Tray 1 is an 8000 PS driver. The driver I use
to only print to Tray 4 is an 8000 PCL driver. They want to be able to print
from Tray 4 using the selected driver even if there is paper in Tray 1. The
issue is that even after using the command "net use LPT1
\\<server>\<printer>" it keeps printing to Tray 1 when printing from the DOS
program or even when using the command "dir > LPT1". When using this same
printer map in Windows, it prints to Tray 4 even with paper in Tray 1. I have
no idea what is going on with this thing. I've tried countless numbers of
drivers to no avail and haven't really come up with anything searching the
forums. Any help would be appreciated!