This is what I bought https://www.diodedynamics.com/store/cat ... gory/1441/
including the Resistor Kit.
I'd advise getting the resistors from ebay or elsewhere, you'll save a few bucks, plus the wire leads on these are annoyingly short.
The included instructions are pretty clear. Basically you cut 12v brake wire (green/yellow on mine), and the 12v turn signal wire; connect them to the module's red and yellow inputs. Connect the module output white line to the other side of the brake wire going to the brake lamp.
For the now-dangling wire going to the turn signal bulb, I just hooked that with a tap into the reverse light line to function as extra reverse lighting.
I did this all underneath the brake light units because it was easiest (3 bolts to remove each unit)
It might be better to take off the rear interior panels and do your tapping/mounting inside the c-pillars, for better moisture protection.
If you get a fast flash because the LEDs draw less current and the car thinks the bulb is out, you'll need to add load resistors on the turn signal line. You can do this anywhere--I put mine under the hood connected to the front turn signals because there was more space to mount them there.