Arduino GPRS/GPS Tracker Shield on Mega


There is little info regarding the Arduino GPRS/GPS Tracker Shield.
It works flawlessly on an Arduino Uno but on a Mega this is another story!
I first had to redirect the pins 7 and 8 to 50 and 52 to be able to communicate with the M95.
But I cannot find how to communicate with the L96 on Serial pins 0 and 1.
Has anyone managed to do so ?
Thanks in advance for your replies.