Clearchannel is broadcasting RDS-TMC, but again this is not TP. The Clearchannel TMC signal is I think a subscription based service so you need an up to date disc. In most of Western Europe the TMC is sent unencrypted, but in Germany I think you can additionally pay for data which is more detailed.

I know the BM54 has two tuners so that it can tune one to the TMC equipped station whilst the other is used for music. Dunno what the BM53 has.

TMC data is sent to the MK4 I think over the iBus (rather than navbus).

Sirius traffic is again a data channel from the satellite that is sent to the nav computer.

The modification to your 4.6i was to change the region to say Europe, which changes the channel raster to 100kHz and cahnges the upper and lower bounds of the FM and AM bands.