I attached my darts by first drilling the holes, then inserted plastic tubes which I glued in place. ( ensuring that the angle was correct by test-fitting a dart when I glued them in place. ) Once the tubes were glued in place, I trimmed them flush to the outside and filled in any holes or gaps. ( aside from the holes in the actual tubes )
Then I used hot glue to secure the darts in the tubes. I can try and post up a pic of the dart setup for you tonight if you'd like.