How do I press the Fn key using a PC keyboard on a Mac?

I am in a bit of a pickle. I am using a Dell keyboard with Mac OS X, and I would like access to my function keys while I'm using Terminal. A friend of mine has a new Mac keyboard which has a Fn key right on it, but when I press the same location on my keyboard my cursor simply turns into a question mark, apparently this is treated as the 'help' key from older model mac keyboards.

I know that I can change my function keys to work properly using an option from the Keyboard preference pane, but I don't want to do that because the ONLY time I need my function keys is when I'm in terminal, other times I am fine with things like volume adjustment etc. so I'd rather have a Fn key. I have also looked in "Modifier Keys . . .", and it allows you to redefine the caps lock, ctrl, alt and shift keys, but not assign anything to Fn (which is a shame, I use Caps Lock as my Ctrl and the 'real' Ctrl would be a perfect Fn key)

So...is there any way to 'press Fn' on older mac keyboards or on third party keyboards?

EDIT: To clarify, my dell keyboard does NOT have a Fn key on it. The place on my friends Mac keyboard that functions as an Fn key is an Insert key on mine.

Solution 1:

You can use an application like ControllerMate to assign custom actions/scripts to keys and controllers.

Solution 2:

I found this post helpful:

http://david.rothlis.net/keyboards/microsoft_natural_osx/

The Function keys (F1, etc) behave as such (as opposed to brightness, volume, etc), regardless of what you set in the Keyboard preference pane. If you press “F Lock” the F keys simply do nothing. Luckily the F Lock remembers its setting across reboots.

There is no Fn modifier key as on the Mac keyboards.

KeyRemap4MacBook allows you to map the F keys to the usual brightness, volume, etc. but then you’d lose the normal F keys.