I have good contacts in Xerox IT having worked there for a number of years. They confirm that the only dedicated 4030 drivers are for W3.1/W98. Usual comment was "why would you want to use that printer anyway? Get rid of it!".
Anyhow, seems like you now have a workaround with the IBM/HP drivers, XIT also suggested that so there's a good chance it should work.
TAFO