With all due respect, you're working awfully hard here.
I don't see a WinMe driver package listed here for that scanner:
So are you using the Win98 software drivers or XP drivers (with a WinMe patch)?
I'd disconnect the scanner and attempt to run a Windows system restore before the install - although given all the directories manipulation it may likely do no good.
If the restore does work, I'd try the opposite software driver of whatever you used on this install (ie: I'd try the XP software if you've been using Win98 or vice versa).
HP imaging software can be [AMIN NOTE: Post Edited per TOU Violation] in and of itself. And now you're putting it on top of WinMe.