The idea here is that the more cold air you can get to your rotors and calipers the cooler they will run. As it is the brakes are pretty much in a dead air zone when it comes to flow.
The first thing you have to do is actually get the air. Obviously your best place is somewhere in the front of the car (duh). If you have a front mount intercooler than you are in luck because you have an unused air scoop on either side of the car. You will need to make some sort of apparatus to attach to the back of this scoop to grab the air and channel it into a conduit. There are as many ways to do this as your imagination will allow. On my car I use some roof flashing that is used to shore up vent pipes that stick out of the roof. I trimmed the large square base to just slightly larger than the vent holes and bent the top and bottom forward. Drilled a hole in each and used a rivet to attach it to the vent. Now before all that I cut down on the "tip" of the flashing a bunch of times so that I could spread it out like pedals on a flower. I stuffed the hose on it, splayed them out more and taped it all together.
You then have to get the hose to the wheels and how you do that is up to you. Just make sure you aren’t going to drag or snag on the ground or get caught up in any moving parts. Zip ties work great to attach everything.
Finally you have to actually get the air as close to the center of the rotor as you can. The point being to stuff lots of cool air to the middle of the rotor so the vanes can suck it up and throw it out cooling the rotor on the way. When I first did mine I just got the hose end as close as I could without fear of it getting hit by anything and attached it to the knuckle. This was good but not ideal . Ideal would have put the air RIGHT there. I haven’t done this yet but if you used some sheet metal or plastic that you melted and shaped using a heat gun you could make a nozzle that extended past the knuckle right at the rotor and you could secure it all up to move with the wheel as it traveled left, right, up and down.
If you do this all right you can do it for less than $50. You can get the 3" hose from most auto stores. It is more durable than drier hose and being only 3" rather than 4" it gives you many more options for routing. If you come up with new and novel idea please feel free to let us all know about it.