You will need to register a company, just as you would a regular proprietary limited company. The company will not need an ABN as it won't be trading, and is a corporate trustee.
When you are creating a trust, it will ask you who the trustee is. You will need to provide the company's name and ACN, and list them as the trustee.
You can then obtain an ABN for your trust, which will be in the name of your trustee (on behalf of TRUST NAME).
Then, depending on your state of jurisdiction, you can get your trust stamped.