I removed the battery, found the big grommet with the nipples on it to cut off. I sliced one off (and half my finger), and figured that was that. Poked a screwdriver through on the engine side.
Found the grommet in the passenger side, but no sign of the screwdriver.
Gave up at that point.
So I think I was 99% there. I can't get the boost tube through on the engine side, so I wanted to push it through on the passenger footwell side. Doesn't help that the sound deadening is in the way and really tough to shift
I've done about 4 of these now.
I trim the top off the nipple closest to the drivers side. Then spray some lube and push a torx 25 screwdriver through from the engine bay making sure you angle it away from the harness.
Then get someone to hold the screwdriver in and push the boost hose on the end of the screwdriver and pull it through.
Doing it this way keeps the grommet the right way so no water can leak in.