Your B6 already has can, you need to bypass the TMC unit and get to the infotainment can instead of the bosch can that your Navi-D uses.
Find the TMC and unplug it all, connect the two TMC antenna cables together. Tap into the canbus leads for the infotainment can at the TMC unit, they are usually orange with stripes (brown and violet) Connect them to your RNS-E and the cluster will work, so will ignition, lighting etc.
Easiest thing to do is jumper the pins on the TMC connector, from the grey can bus wires to the orange ones.
Make sure you get them the right way around. It wont work one wa, it will another.
Find the TMC and unplug it all, connect the two TMC antenna cables together. Tap into the canbus leads for the infotainment can at the TMC unit, they are usually orange with stripes (brown and violet) Connect them to your RNS-E and the cluster will work, so will ignition, lighting etc.
Easiest thing to do is jumper the pins on the TMC connector, from the grey can bus wires to the orange ones.
Make sure you get them the right way around. It wont work one wa, it will another.