Is there a How-To on headlamp dismantling for a 2009

That's unfortunate, there is no way on earth that the Permaseal will come apart in water and a heat gun directed to it for long enough to melt it will also melt the plastic or discolour the lens, you need a oven to stand any hope of opening it so your idea of going to a breakers yard is sound. 

Its probably be broken by a previous owner and they just brought the cheapest part they can find not thinking about the colour

just watch out for fixings being broken, its all to easy to get a cheap lamp that wont secure properly or is cracked, usually the cracks are on the back pointy corner where the side light is inserted, this seems to be a weak spot in the plastic and isn't very obvious at a glance that it may be broken, there are two interchangeable clips on the bottom that can snap, as long as you have one to put under the high beam it will be fine, the other one has never clipped on properly on any of the lamps ive had, another point of weakness is the on the back lower corner next to the indicator, there is a little hole where a clip from the bumper support bar slots in, not the end of the world if that's broken but if that is gone along with some of the other fixings then it can wobble about.

The final point of fail is the plastic tab at the top which you bolt down, if that's broken, forget it, ive seen a lamp shoot out of the car under breaking when that's not been secured! :)