Shoot dude, what did you use to cut the carpet?
Using a utility knife (with a sharp blade!) you can make some slits in the carpet going back to the closest edge and slide the bar in. Better yet, pull the carpet back, install the bar and tighten it up, then start to get the carpet settled around the bar. You can make out where I cut my carpet in this pic:

I first installed the bar, then made the cut in the carpet to fit it around the bar.
Another nice benefit of this method is that the cut, although it doesnt show up much as it is, is hidden from the view of the open trunk by the bar itself.
To others who do this and use the method described here, just take a little extra time and cut an inch at a time in from the edge until the carpet starts to sit nice and flush again. That way you ensure you're cutting the slit in the right direction towards the point the bar protrudes through the carpet.