The soft rubber like material that is around the outside of the connector must be trimmed back.
If you use a new blade in a shop knife it cuts very easily.
Trim around the outside back a little more than 1/8" probably more like 3/16". Under the soft outer coating is the harder plastic that the threads are part of. This cut will reveal a shoulder that is molded into the hard plastic with the threads . The shoulder will keep the connector from pulling through the speaker housing and there is enough thread length there to extend out through the housing and the leather just don't drill the hole larger than 3/4".
It is very very difficult to hold the connector from the back side, the cover open and in position from the outside when trying to get the retaining ring started on the threads. Be very careful not to cross thread the ring and don't over tighten it when you do get it started.
Sorry I didn't take some pictures when I did mine. The hardest part of the whole job was getting that little ring started correctly on the threads and to get some pic's now I would half to disassemble it and I really don't want to go through that all over again.
Hope this helps!