Default values are for #6 screws, but thats easy to change. YAY parameterization!
You bolt them on instead of glue, pretty self explanatory. At first I was worried that using one bolt would cause problematic torsion, but in practice that dosen't seem to be a problem at all. Make sure you mark where to drill accurately. I used the bushings themselves as a template. If you don't want infill, you better make the tabs thin.