Comment 24 for bug 1094744

Thank @Anthony, but i got a similar solution based on your recomendation and recomendation on http://wiki.ubuntu.com/Multitouch/AppleMagicTrackpad

#some parts of this comment are based on http://wiki.ubuntu.com/Multitouch/AppleMagicTrackpad

In a terminal:
1. Install input-tools, to determine the physical (model-specific) and unique device IDs from the output of lsinput
  sudo apt-get install input-tools

2. Create /lib/bluetooth/<physical_ID>/pincodes as the root user (or with sudo):

 # This folder *should* already exist, create it with 'sudo mkdir' if not.
 # You can use TAB to complete, if it's the only Bluetooth device on your system:
 3. cd /lib/bluetooth/<physical_ID>

In my case, i wrote:
cd /lib/bluetooth/74:2F:68:CE:17:57 <-- change for your physical_ID

 4. sudo gedit pincodes
5. Add this line to the new file, save, and exit:
     <unique_ID> 0000

where <physical_ID> is a backslash-escaped physical device ID, like D8\:30\:62\:38\:18\:02, and <unique_ID> is your device's unique ID, both from the output of lsinput.

I applied it and works fine for me, on Ubuntu desktop 13.04 64 bits.