G'day Gavin,
Sorry to say that to do the job properly, the Grille needs to be dismantled, completely.
There is a tool for replacing the "Bullets", and it is PN. J 8437
Not sure where they can be purchased, but shouldn't be that hard to make.
But, the biggest "killer" is getting everything back in the correct order. This is where notes and pictures come in VERY handy. You ARE taking pictures of your restoration, as you pull it to pieces, and putting it back together?
Bruce. >:D