It'll work the same as an I/C spray kit works on an A/A IC.
However, you have a problem. The water must circulate through the radiator and then into the IC. So let's say you're on max boost for 5 seconds or so. During that time you're spraying water/meth. It'll probably take 5-10 seconds for the water to get to the IC core. Then it'll take some time to bring the IC core down in temp. Realistically....it's not that effective unless it's running all the time.
AWIC setups may be great to reduce heat soak, but changing the system temps rapidly doesn't work.
I would skip the spray part. You can use a small motorcycle radiator that has a fan built in. Only use the fan when you are going to be on the power for a while or small tracks. The water in the intercooler will not warm up if you are doing short bursts but a 1/4 mile pass will turn ice water into warm water, in my experience.
Motorcycle radiators and fans are very compact and reliable, no maintenance! Hide that sucker anywhere
I like the Impreza wagon 2 pump w-washer bottle Idea.
All you need to do is get a micro switch (WOT) from a mid 80's to early 90's Golf or Jetta (from a u-pull-it) to trigger the pump @ WOT when the system is activated (relay powered up).
I would not spray washer-fluid (or any other Meth/water mix) though I'd just spray water on the IC/Heat exchanger core.
I did this to a Ghetto turbo Sentra with a TMIC & it worked well, but the car had no w-washer when I was done...
I just hope a car with slicks does not make a pass after something like this is used on the track as it will get ugly very quickly.
Motorcycle radiators & fans do work very very well & would do an excellent job if you can fit one one the car.