It clamps around the oil cooler itself.... stick a thin line of foam tape along the top and bottom edge to stop it marking the oil cooler itself ( if you so wish)
Slide the grille up between the beak and the cooler ( it should go with a little care) push the bolts through, and the clamps go at the back... a bit fiddly but once it is on forget about it. You could add a blob of locktite for peace of mind