Well Sir, this depends on just how well acquainted you can get with your Buicks lighting system. Some don't like to delve into car wiring/lights and some do. Wiring your toads lights and using the factory lights is not a very hard project. I don't blame you if you don't want to tackle this. I've been doing things like this for decades so, it's one of those things that kind of come natural.
I just did our brand new Honda CRV and it was a piece of cake. You can use the diode kit you mentioned and that's fine but, a diode is a diode and I got a 4 pack of diodes at Radio Shack for about $3.50. I also wanted our new CRV tail lights to work just like they do when we're driving it. I wanted ambers to blink and reds for tail/marker and brake, just like normal.
Now, one thing here. The coach we've got has what's called a "two filament" system, and the CRV has a three filament system. In order for the lights on the CRV to work correctly with coaches lights, I had to install a "Tail light wiring converter". That converter converts the signals from a two filament system to a three filament system and makes everything work just flawless. It cost me about $30.00 locally but, you can get yours from a local shop too in your area or, you can go to etrailer.com and they've got them too.
Below is the wiring diagram that I drew up pertaining to how I did the job. The main difference in using the diode kit and using the ones from Radio Shack is that you have to solder the Radio Shack one in place and the ones from the kit you can simply use spade connectors and some crimp pliers. If you look at the diagram and study it for just a minute or two, you'll see how simple it is. See if it's the way you'd like to go.
When done, you're Buick's lights will act just like they would as if you were driving it.
P.S. If you'd like any more info, just PM me and I'd be glad to help.