OK Roberta, first of all this is the weirdest driver situation I've ever seen.
For some bizarre reason HP does not offer 4M Plus drivers for Windows 9x (I've verified this with an HP tech), even though they have links to download that printer's driver for Windows NT/2000/XP and even DOS and Windows 3.x!! Evil bastards, they be. I've also searched other driver sites & it is simply not available. I even found a number of people posting questions on other forums with this same problem.
Yet it's on every Windows setup CD!
At any rate, I did complicate this by linking to the LaserJet 4M Plus AutoCAD download for Win98. I only realized after trying to install it myself that it actually isn't a driver at all (so it wouldn't work even if you installed AutoCAD), it was simply listed as the only HP 4M plus software download for Win98 alongside all the the proper drivers for other versions of Windows.
SO DO WHATEVER IT TAKES TO GET AHOLD OF THAT WINDOWS CD!