I have completed the update to software 6.7.0 with map 2016 v1 and the process is fairly straight forwards assuming you have joined My Toyota and registered your Nav unit.
Log into My Toyota
From top menu select "e-store"
Then "maps"
"Map update 6.7.0"
If you have multiple cars registered select the correct car, if you are entitled to a free update select "Set FUD" and then follow the step by step instructions to verify your free update and obtain the code required during installation in the car.
One point to mention once you have verified you will need to wait for an email with a link to the software download, at the moment the servers are busy and my email took 5 hours if you want and have the verification code you can obtain the download directly from
www.toyota-tech.eu :
"Owners"
"Navigation system licence key activation"
Here you will see options, only the first two apply for the Touch 2 & Go(Plus) to confirm if you have either High ( Go Plus ) or Low ( Go ) you can see the version on My Toyota as either 6.7.0L Low or 6.7.0H High follow the instructions to download , you will need atleast an 8gb USB