SIXAXIS needed to be paired with N900. You need to know the BT address of the phone. Go to Settings -> Product information and find out your Bluetooth address: 34:7E:39:4A:37:XX. ok i know where to find my mac addres.

Then you need to connect PS3 SIXAXIS to your PC with the USB cable. DONE

Use the sixpair tool. You may compile it yourself: I EXTRACTED THAT, NOW WHAT?

sudo apt-get install libusb-dev
wget http://www.pabr.org/sixlinux/sixpair.c
gcc sixpair.c -lusb -o sixpair

or just download my precompiled binary.
Next, write your N900 Bluetooth address into your controller:

sudo ./sixpair 34:7E:39:4A:37:XX # your N900 BD address: WHERE DO I WRITE THE BLUETOOTH ADDRESS

Windows should download Linux LiveCD and use it to run sixpair.
Install software: DONE, BUT WHERE DO I GO FROM HERE?

Install
Open Web Browser (MicroB) on your N900 and tap the green install arrow: I GOT THE SIXPAIR SUPPORT FROM THE EXTRA REPOSITORY ALREADY. THE CONTROLLER IS PLUGGED INTO MY PC WHILE RUNNING UBUNTU. WHERE DO I WRITE THE MAC ADDRESS OF MY PHONE?????????.UBUNTU IS FOREIGN TO ME. MAN I MUST BE THE STUPIDEST PERSON IN THE WORLD BECAUSE THESE INSTRUCTIONS GOT ME SCREWED UP.

Usage

1. Activate Bluetooth on N900
2. Press PS button on controller – this will launch sixad via udev
3. Wait for the BT icon to turn blue and sixaxis LEDs stop flashing
4. Map keys in your console emulator settings by pressing buttons on controller.
Left stick simulates mouse movement, right stick simulates scroll wheels, directional pad simulates arrow keys and buttons are mapped as on the following picture: