Yeah, it's something like the quarter-finalists from the Intermediate Cup and the semi-finalists from the Junior Cup. Not sure on exact mix these days
The Intermediate Cup was always a qualifying competition for the FAI Cup going right back to the formation of the State. B teams, who competed in the LSL top flight for decades, were in the Intermediate Cup but couldn't enter the FAI Senior Cup (except when UCD's LSL team qualified in 2009 - don't know how we got away with that in hindsight, but the rules were changed subsequently)