I've done this on a slightly more ghetto level....it came out pretty decent but it was a metric ton of work...I can sum it up in pics.

we took this.




base coats made the garage look like this









and it ended up like this.



We spent about 4 days sanding and prepping and primed it and painted it in a weekend...as you can see we didn't mask the walls but covered most everything in the garage with plastic. I used Omni single stage paint and it came out pretty well. We also did this in Feb IIRC and we cranked up a salamander heater (not the safest thing in the world) to 90*s or so to help drying in between coats. The most important thing is to have a compressor that can keep up with your spray gun of choice, make sure you note the CFM the gun requires and take breaks when the compressor doesn't seem to be keeping up....a water separator is crucial.

That being said I would avoid doing it again if I at all could, the prep was a ton of work but the painting part wasn't bad at all. We did 3 coats of base...if I did it again i would have done a couple more. My buddy STILL has pink dust in his garage but it was a new,fun experience for all of us and as you can see we have good senses of humor. (edit, had to remove a few pics due to forum restrictions)