I've already tried something that was suggested on an old post around the kvr forum:
This still didn't work, when turning for example the knob while midi mapping in ableton, it simply won't map in whatever i selected, nothing appears to be assignable. Any ideas why?When using the Ableton Live template, the encoders default to transmitting in 2's Compliment format or what we call MIDI CC (Rel). This means that when you turn an encoder clockwise, it will send messages to increment the parameter and when you turn the encoder counter-clockwise it will send messages to decrement the parameter. This way you won't get jumping parameters if you move them with your mouse. Live should identify that encoders are configured this way automatically.
If you would like to change the format of the encoders follow these steps:
Press the button below the display, labeled setup
Use the Data Encoder to select 'Control Edit' from the menu
Press the display button labeled enter
Move the encoder you would like to re-assign
Press the display button labeled with an up arrow to select 'Message Type'
turn the Data Encoder to select 'MIDI CC'
While you are in the Control Edit menu, you can continue to select encoders and change their Message Types
Press the Internal button to leave this menu