It's gonna take a little time and a lot of 4 letter words.
You have to push the black plastic ducting back with your fingers and angle the piece into the opening and work it into place. It's better to get the top in place first, because if you scratch up the paint inside that opening no one will ever see it unless they lay on the ground and look up into your front brake ducts. Good Luck!
Seems like mine just went in from underneath after you pull the vent back from the nose. Then they are "captured" in between the fiberglass and the vent plastic tubing. Really was a lot simpler that I thought it was going to be. I used a pair of medical foreceps to hold and positon it through the front opening when I was working on it.