The Vaeth version was - let's say - not working in every car.

If you want a solution that really works, contact Evotech Motorsports.
They've done an adaption of the 32 AMG M Mode.

This modification was done to different SRT's over here in germany and it works perfect.

Contact Mr. Neumann
Evotech Motorsport | Home

And concerning the manual tranny. There's no MB manual tranny that can handle the torque of the SRT6. There are trannys for Diesel versions. But as far as i know they won't fit. And if you find a mechanical solutions, you'll also have to handle a lot of electronic items.

Regards
Markus