Re: tools needed for alfa 156 2.0ltr twin spark
Make sure you change the balancer shaft belt and balancer shaft belt tensioner as well, as these do fail and can take the cam belt off when they go.
You could do with some torx bits, ribe bits (look like Torx but with square points instead of pointy points, if that makes any sense at all...) and the aforementioned cam locking tools.
Do you have the diesel noise? May as well do the variator at the same time if you do.
You have to take the cam cover off, so a gasket for that will be handy.