simply J

I was going to bring my car into Rojo collision to be fixed tomorrow and have a s4 bumper put on. the trouble is they said that doing the Rs4 conversion on the s4 bumper would be too much work. I could do it myself if I had the bumper, but then how do I go about getting the whole repair done? If I bought the bumper myself, did the conversion and then brought the car into the shop in a couple days, how would the insurance coverage/payment work? Is that even possible to do? TIA