And Boom Goes the Dynamite will see you flying around Steelport in a pimped-out, purple Vulture or Tornado giving overhead cover to Kinzie while she has her way with the Deckers and Pierce while he screws with the Morninstar.
Compared to the Tornado you had to use in SR2, this is actually quite a lot easier to fly and the weapons are a big improvement. LT will fire the rocket pods (homing missile on the Tornado) and RT will fire your chaingun - I found the chaingun to usually be the better option as you don't need to lead the target cars by anywhere near as much and there's less chance of a friendly-fire incident.
You can hover in position and swivel the chaingun turret around to engage any gang car (marked with a red triangle) - two or three solid hits should set it on fire.
Then it's just a matter of following your homie to each location (three, four or six depending on difficulty) and blowing up each marked car.
There will also be the odd attack helicopter show up - these should be easy to pick out as the red triangles will point up to indicate they're higher than you - but the chaingun should make quick work of them too.