How can I turn off a penger side airbag in a 2000 Chrysler Concorde?

I have 3 children (ages 8,7 & 4) and only 2 rear seat belts with shoulder straps. By law, all booster seats have to be used with shoulder straps, meaning one child has to ride in the front. They make reto-fit kits to install shoulder belts in the back seats, but they aren't available for the center seat. I would like to turn off the airbag to better protect my 8 year old. Any suggestions?