I asked a similar question last year, and here is the answer I received from Stangnet member "007":
"Unfortunately there is no way to install the bar without cutting the holes in the top of the trim. Its the ones in the front that are unnecessary. They give you four black plugs to put in the holes that you cut, but it looks like crap when you open the door and can see them.
Tips: Be very careful with the bar. The vinyl is very thin, and rubbing it against something can easily scuf it up good.
My seatbelts didnt want to come out, and they didnt need to either. I just pulled them out to the full extend and hooked em round the seat or something.
When you come around to tightening the bolts to hold the bar in place, just skip cutting those circular holes in the front of the trim. Instead, you can sit by the open door and reach in the side of the trim. You have to bend the trim a little and reach in with an allen wrench, but you dont have to cut any extra holes.
If you plan on upgrading your rear speakers EVER then do it at the same time. The bar has to come out again to swap them."