TempDB on Shared VHDX
As far as SQL Server config: Since you're not using SQL Server clustering with shared storage, I believe you don't need to do anything but configure all your instances with Tempdb on T drive (or whatever standard path you choose). See Example A at https://msdn.microsoft.com/en-gb/library/ms345408(v=sql.110).aspx.

As for how to ensure that T drive is available as local storage in all your VMs for when SQL Server starts up, that someone else will have to help with (perhaps stackoverflow with virtualisation tags).

And be sure to test your whole failover process, don't take anyone's word for it.