Here is new reports from obdstartool engineers, who have managed to use the original OBDSTAR X300M programmer to change km/ mileage for Cayenne before the 2009 year.
The X300M main unit and its manual：
the dashboard of Cayenne 2008
the current mileage: 2345744km
note: check connection of the car and X300 M
here goes to Cayenne odometer correction.
select VEHICLES->MILEAGE ADJUSTMENT->PORSCHE->PORSCHE V30.12
select Cayenne->Cayenne -2009->MILEAGE ADJUSTMENT
->enter a file name to save, here 11100000
input value: 11100000
X300M programmer managed to read the current mileage of 234560 (error does not exceed 10km)
->input new mileage: 345430
input value: 345430
the dashboard displays the new milesage as what is set just now
Cayenne change km SUCCESS.