Luckily we support Autodesk Eagle natively, so the steps are very very simple ;-)
We offer an EAGLE Design Rule File which includes our layer stackup and all necessary design rules. Have a look at our Github.
Note for 4 layer boards: Please set layer definition to (1+2*15+16), otherweise we won't recognize all 4 layers of your design.
We supplort Eagle file format natively. Just Drag'n'Drop or Upload your Eagle-Board file and you are good to go.