Booting to single user mode using a non-mac keyboard

Connect the keyboard that came with the computer.

I use MS 3000 Media keyboard, the MS keyboard driver allows swapping Windows and CMD keys and the Application key or something, and works fine and I can use ALT instead of OPTION and CMD + s

The key with Windows Start menu logo is what I use on left side; on the right side, the key to the left of the Ctrl key (not sure of its name, or function).

Apple "official" keyboard isn't required.

No, but they require a keyboard that can be configured to produce the required Mac commands rather than Windows commands. Note that the Windows key on the keyboard is not the same as the Mac's COMMAND key. The Windows key produces the CTRL key. The ALT key should produce the COMMAND key.

At startup time, no driver nor the OS is loaded, so it doesn't matter what modifier key (Caps Lock, Control, Option, and Command) remapping the driver or OS X Keyboard system preference allows. At startup, you need to use whatever one is hard wired in the keyboard to the key code of the appropriate modifier key. Once the Mac starts up & the driver & system preferences are loaded, then use the remapped keys.

This site:
[What are the Windows keyboard equivalents for the Mac's special keys?|http://macs.about.com/od/faq1/f/windowskeyboard.htm]
gives the following:
----------------
Mac key – Windows key:
…………
Control – Ctrl

Option – Alt

Command (the four leaf clover) – Windows

Delete – Backspace

Return – Enter
------------

However you might not have a keyboard issue at all, but rather a "firmware password" might be set. To test for this, try booting with only the alt key (equivalent to the Mac option key) held down. Do you get a screen with a padlock and a password entry box?

Yes - take a look at:
[Setting up firmware password protection in Mac OS X|http://support.apple.com/kb/HT1352]
and
[Open Firmware Password utility in Leopard|http://throwable.wordpress.com/2008/03/01/open-firmware-password-utilit y-in-leopard>

Karunamon wrote:
Judging by the links I just read there, I should be able to do cmd-opt-o-f to boot into open firmware, give the password, and then simply disable the protection.

That doesn't work either, however, despite this machine being a 2008 Intel iMac

It doesn't work because only PPC Macs use Open Firmware. Intel Macs do not.

Do I have any other options that don't involve digging up my X disc?

No.

I need to get into single user to attempt fixing a disk issue..

Why don't you tell us more about your particular issue?
For instance, if you can still boot normally you might be able to create a bootable clone on an external drive, re-boot from that clone, and then run Disk Utility from there to repair your internal HD.