Need a controller...
 

...that will process 2- 5V inputs, "AND" circuitry.

In other words, I want both conditions to be met in order to mist, one input is IAT, the other is boost.

Any ideas?

The boost control is easy, use a normally open boost switch. As for the voltage I'd get down to Maplins, I'm sure I've seen some kits like that on their shelfs.