I made up this tool after getting fed up with the rubbers disappearing into the fairing.
. Used a long bolt and nut plus a penny washer.
You need to position the screen first and then put in the two front grommets first. Sliding a hand down on the instrument side to support the screen as you push the grommets in using the tool. WD40 or similar helps the grommets to slide through. You need the "bulgy" bit of the grommet behind the screen not between screen and plastics. The two side grommets should then go in easily.