That's not the right grommet then. From inside the car it's up even higher, and slightly closer to the driver's side. You just have to pull the carpet down a little bit, and reach your arm up under the rubber padding, there's a stiff cable going through there (think it's the hood release, but I can't be sure)
It's got a round rubber plug that you can either pop out of place, or you can puncture to feed a wire through (I used the prior option)

^Where the red power wire is going in.