depending on what you boolean sometimes the two things just VANISH for no particular reason

i would think that boolean operators to create the vents wouldn't be so bad and it would be quite a quick way of doing it... provided things don't just vanish

however, like alexanderH said, booleans can do annoying things to your geometry

i'm not sure what he had in mind when he said that but if you look at one of Kurt's tutorials (like the free dog tutorial) you'll see why booleans can be a pain in the ass.

sometimes it's just faster to just cut faces up and make the vents yourself

although, you might benefit from trying booleans and then trying extruding the vents

you just have to keep all faces with 4 edges each