No problem
It works!!!
I've patched the Info.plist file using
patch Info.plist Info.plist_src
where Info.plist_src is the patch, then rebooted.
After then I ran
sudo touch /System/Library/Extensions
sudo kextunload /System/Library/Extensions/FTDIUSBSerialDriver.kext
sudo kextload /System/Library/Extensions/FTDIUSBSerialDriver.kext
and finally the virtual serial port appears!!!
To view the GP boot I use "screen" that is installed by default on MacOsx like this:
screen /dev/cu.usbserial-FTT65Q1RB 115200
Thank you for the tips, darek