There are locking tools for the cams 2off part# 88713.2282 but you can get away without them.
The 'allen key' method is explained in detail here
http://www.ducatisuite.org/belttension.html
check out
https://www.gatescarbondrive.com/products/tools app, it's meant for bicycles drive belts but works well.
There's also a tensioner included in JPDiag, if you have a laptop and a remote microphone.