Using a GPS? Depending on the version, you will have to enter Voeren or Sint-Martens-Voeren as town.
The hostel is not easy to reach by public transport. Take enough time.
Plan your route
It's best to ask parking advice when you arrive. Here are some options:
Coaches cannot drive to the entrance of the hostel via Komberg. They can park along the road at Kwinten 3, Voeren. From there you can take the steps to the hostel.