You disembark either at Innsbruck and then take the bus to Lienz or you disembark in Wörgl and go via Kitzbühel to Lienz. The Nightjet service between Hamburg and Innsbruck also carries cars and motorbikes. The entire journey, including the express bus to Lienz, can only be booked through the ÖBB (Austrian Federal Railways).
Osttirol is also easily accessible by day and overnight train services from Italy. The Trenitalia website shows all available options and connections.