Per their guide the Naga has 2 modes - Basic in which the thumb grid acts like your number row above alpha keys and NUM which they act like your numpad.
Their software lets you setup macros for the buttons but I don't see how it could be done without affecting your numpad or numrow.
"USING BASIC  AND ADVANCED [NUM] MODES
The Razer Naga provides a 12-button [1-12] Thumb Grid in two modes: Basic  and
Advanced [Num]. To change between the Basic  and Advanced [Num] mode,
simply use the switch at the bottom of your Razer Naga.
In Basic  mode, the 12-button thumb grid works the same as a keyboard’s
numerical keys. These buttons allow you to replicate the action bar of most games onto
the thumb grid buttons.
In the Advanced [Num] mode, the 12-button thumb grid works the same as a keypad’s
numerical keys. These buttons allow you to have quicker access to in-game commands
without having the need to reach for the keypad.
Note: Pressing the “Shift” key while using the Basic  mode will change the thumb grid buttons to their
secondary functions (for example: !,@,# instead of 1,2,3)."http://dl.razerzone.com/master-guides/N ... MG-ENG.pdf