Harddrive as Scrollwheel for PC

My goal is to take a Hard drive's platter and motor assembly and make it into mouse-wheel-like Scroller for a computer.

I have found the HDDJ Project on Instructables, as well as a thread from Ladyada about using an Arduino to emulate a USB mouse.

In accordance to the Instructable, i will need 3 comparators to switch the analog output to digital that the arduino ?could read better?

What sort of code would I have to write for the Arduino to achieve this effect? Below I have a link to the firmware of the HDDJ below, but it is based off of a straight microcontroller, so I cannot tell which code drives the controller and which code is actual logic.

My circuitry/electrical skill is practically nonexistant, but I do have two years of coding in C++, so I can usually get general concepts, but i have never written code before for Arduino, so it's really all new to me.

For Ladyada thread
h##p:/www.ladyada.net/forums/viewtopic. php ?f=24&p=37113

For HDDJ
h##p:/www.instructables /id/HDDJ_Turning_an_old_hard_disk_drive_into_a_rotary/

For HDDJ Firmware and Driver and Plan,
h##p:/www.instructables /id/SCE6QVVFN82OEYN/
(i apologize for the formatting, but i couldn't add links w/o one post, and i'm not about to pull some obnoxious "F1RST!!!!!" BS)

If anyone could tell a newby whether this is possible or not, i would be very thankful.

Thank all,
eagle

You will need three analog comparators, in hardware. They convert the analog voltages from the disk moto into binary 0V/5V signals for the Arduino. Once you have those wired up, you can start to think about software.

Suitable chips are the TLC3704, LM339 and similar. You can connect a LED to each output pin to monitor operation, without involving the Arduino.