Now I was in possession of a broken mainboard.
Since the JTAG pinouts are unknown till this date, I stripped the mainboard from all its components and traced the board in order to find the JTAG.
Had to make new probes from some needles in order to trace from the BGA-Grid..
The difficulty here was that the test-pins where on the other side as where the MPM 7200-A was, and with those tiny bga-vias it was real hard to trace.
Some pictures of the board (before stripping)
The front side of the Mainboard (it is a single board device, apart from speakers, LCD and antenna no further external parts, all on one board!)
Backside with foil still on it (this side is facing the front of the device)
Backside without Foil and here are the JTAG testpins:
The Pins I traced:
Mode 0 (between TRST-N and TDI)
Will be checking for other pins on request (btw: sofar watchdog, mode 1,2,3 are not (yet) found)
These should suffice to JTAG the device.
For those in need of testpoints for reference voltage etc..:
Memory module (on this board):
More info Regarding JTAG as being used to debrick HTC Dream