This issue has been fixed on own since its posting, but here it is.
Q: I need a few of the F keys, mainly the ones that change CPU amount, the reason being that my iMac uses these keyes to adjust the volume. Does anyone know how I can reconfigure DOSBOX to use some of my available keys so I can get back into making custom levels?
A: I don't know whether remapping them for DOSBOX is possible, but that appears to be what the "fn" key is for... interesting.
Since the topic already exists, it can be used for issues related to OS X and DosBox.
That's easy.
1: Hold down the Fn key while you press the Function key.
On an aluminium keyboard, that's above the Delete key.
On a MacBook keyboard, that's second from left at the bottom.
2: OR you can disable special keys in System Preferences > Keyboard.
Untick "Use all F1, F2, etc., as special keys" and then you won't need to use Fn.