Can i add Steering controls to my 96 Bonneville SE...?

Um...

Well, you're probably going to need extra wiring harness down the column and perhaps a different steering wheel, not to mention an audio front-end unit with the correct wiring harness connections in back of it so it can be driven off the steering wheel controls.

It'* not unheard of for the base-model cars to carry wiring harnesses for options that weren't actually on the car (e.g. to account for dealer-installed options that might be put on later), but retrofitting steering-wheel controls to a car that didn't have them is something I haven't heard of before.

If you can spend some quality time pulling apart a junkyard donor, you'll get a good idea of what you need to remove and swap over to your car in order to do this. (I assume you've found one already and are not planning to pay retail for the parts you need.)