There's a policy to raise your liberty desire; depending on the integration level you started at it may take more or less time to get to the suzerainty level at which point you can declare an independence war.

Is there a different path for a French fealty? I don't get the policy as Burgundy.

As a French fealty you need to conquer as much land from other fealties as possible; once a fealty hits 80% of France's strength the fealty system will revert to standard subject types.

Very cool, thanks!