I actually just replaced mine.
Smear it with some oil to help it slide through, use a flat head screwdriver to get it through the top of the intake manifold, then maneuver it so it sits even on top of the port for the valley pan, then I used a same size socket with a long extension to hammer/tap it in place. I also used a socket with the extension to tap in the pcv once the grommet was in flush.
Good luck.