Yeah, it's a shame that HP has deleted those old web pages. Your's is not the first complaint.

Did you try the other steps listed in post 8 of that thread?

"Clearing CMOS
Using F10 Setup to Clear CMOS
The instructions that follow allow you to clear CMOS and reset the computer to the factory default values.
1. Access Computer Setup by pressing the F10 key when the Computer Setup (F10 Setup) message appears in the lower-right corner of the screen.
If you do not press the F10 key while the message is displayed, you must turn the computer off, then on again, to access the utility.
2. Select File! Set Defaults and Exit.
All passwords are cleared when CMOS is reset.

Using Power Switch to Clear CMOS
To clear CMOS when you do not know the password turn on the computer using the power button. After the computer has started, hold the power button depressed for four seconds. The next time the computer is started, the system will overwrite the existing CMOS with the valid CMOS from the factory’s original ROM flash of the system board.
All settings and passwords from the last good boot will be restored.