Had some developments in the ongoing saga of the Howtek D4000 drum scanner. Turns out that my Mac G4 tower is just about perfect for this setup. Still has OS 9.2.2 installed on it, looks like it was never used so is very clean and orderly. The OS X has been updated to 10.4.11 (Tiger) but I believe I could update it to 10.5.8 with no issues. I may do that down the road.
Short recap of my setup:
MDD (Mirrored Drive Doors) Mac G4 tower with OS 10.4.11 and OS 9.2.2
Howtek D4000 drum scanner, was at R531 and now at R535 firmware
Trident 3.5.5 and 4, both downloaded from Aztek's site
I had been trying to run some of the freeware/demo versions of software attainable at the Aztek website's Howtek support section but was unable to get any of their programs to talk to the scanner.
Getting it booted directly into OS 9 gave the drivers a direct shot rather than trying to work through OS X's Classic emulation and so it could talk to the scanner. I updated the firmware through MacUtil 3.7 to the R535 version (last released). As I'm writing this, Aurora 4.0 is doing a pre-scan and I will see if it gives the heavy errors (what look like skipped lines, blurring along high contrast edges and generally less than the quality I have seen in other scans).