well basically the most important part is the misting nozzels. i believe that either home depot or lowes carries a porch misiting system and i would assume that it could be adapted to work in this situation. besides that you will most likely need to order misting nozzels off line from a place such as barrs (i think barrs.com) that will be the hardest pice to find, but i believe they are relativly cheap from that site. asside from that you will need a pump sprayer, like used by painters, exterminators and gardners. then to control the timing of when you want it to go on and off you need a regular garden hose timer, this will be the most expensive part of the project at around $30 for the digital one i got. asside from this all you need is the appropriate tubing (should be about 1/4" from the misting nozzel from barrs) as well as reducers to bring the missing nozzel size hose to the garden timer then from the garden timer to the pump sprayer with the wand cut off. now all you need to do is to set up the nozzels, set the timer and pump up the sprayer.
thats a simple system which is relativly cheap. only downfall is pumping and filling the sprayer which could be solved if a faucet could be attached to the garden hose timer instead of the pump sprayer.
hope this helped some