I did bought the same xingling mini bt keyboard, and it is completely compatible with the native bt keyboard driver that already comes with the atrix, there is no need to download any other driver. All you have to do is to press and hold the pairing button for 3 secs (the one on the upper right) than select the keyboard on the atrix bt control, than enter the code 0000 on the atrix when asked, press ok, than imediately type 0000 on the keyboard than press enter on the keyboard. VERY FAST timming it is at the essence here.
Now I'm trying to find a case that uses both the atrix and the mini bt keyboard.
P.S. After pairing for the first time you still have to type 0000 + enter on the keyboard every time you turn the keyboard on :P