I have recently purchased a Mad Catz R.A.T.M as a replacement for my previously failed attempt at getting a decent mouse to use on the go, and found out that all official support stated that Windows 8 is the only supported operating system for dongleless use.
If you try to pair it, this is what happens:
A simple experiment proved that there is a way to at least make it work on recent Macs. Even if the device shows up as it is open for pairing, this isn't the case and it needs to be forced into a special pairing mode.
For this to work, your Mac needs support for Bluetooth LE. This superuser thread covers how you can determine if your computer has support for it or not. Without support for this, your computer will not be able to see the mouse at all.
So you start out that dialog anyone who has used Bluetooth devices is familiar with:
To kick the device into pairing mode, you need to do the following, according to their documentation:
Press the Precision Aim button and the wing button for 5 seconds.
Except, you don't know what those buttons are. The wing button (Button 11) is the button to the immediate left to the left button, and the "Precision Aim" button is apparently "pressing" the 5D button (Button 6) which in turn is the D-pad on the left side of the mouse.
After you have the Bluetooth pairing dialog ready, move your mouse cursor right on top of the "Pair" button and be prepared to press. After you are ready, press the 5D button (no directions, just press) and the button to the immediate left to the left mouse button for five seconds, and the blue light will stay on for about 0.5 seconds.
Press the "Pair" button on the settings dialog the moment you get the long blue light. (The window is really short, and it seems to be picky with the timing) If you fail, just repeat this several times.
If this doesn't work, I'm afraid there isn't much I can help you with - this worked for me and it's here in hope it helps anyone else.
Note that this will unpair it from the bundled dongle, which means you will have to manually pair it back if you want to use it with the dongle, and Mad Catz customer support will probably not give you any useful replies in the event anything doesn't work while using native pairing since this is not officially supported.