Assigning F5 and F6 as shortcuts without using FN on unibody Macbook

[Luigi239]

I have the original unibody Macbook without the backlit keyboard, meaning that my F5 and F6 keys have no assigned usage. I would like to set them to control some system functions such as spaces, but in the spaces preference pane, I am only able to set F5 and F6 as a shortcut if I add the function key.

Is there any way to assign these keys so that they work in the same way as the volume control, iTunes control, and so on?

Thanks!