First of all, do you ferment it just like a "regular" beer?
Depending on the style, yes and no. If you're using certain souring bugs, or are trying to replicate certain traditional fermentation techniques, you might have to do things differently. For simple lactic or brett cultures, not so much. This is an advanced topic, so there's not a single simple answer.
Also, is there anything different with the mash or boil for sours?
Again, yes and no. Some sour styles have very unusual traditional mashing techniques, but there's no reason you have to follow them when making your own sour beers.
Before you commit to brewing 5+ gallons of sour beer, though, you need to do more research.
Try good commercial examples of the various sour beers (http://www.bjcp.org/2008styles/style17.php
) to discover sour beer styles you like.
Experiment by adding vinegar, lactic acid, lemon juice or other acids (e.g., malic or citric acid) to your finished beer. This will give you a sense of what type and level of sourness you like. You might find that traditional sour beers aren't to your liking and you're perfectly happy adding a bit of fruit juice to your glass of beer.
If you do decide to brew a sour beer, you can cheat by adding food-grade lactic acid to your brew or mash using acidified malt (sauermaltz) in order to get lactic sourness.
If you decide to actually inoculate your beer with microflora, you'll need more equipment. To avoid cross contamination, you'll want to keep soft plastic items use on the cold side when brewing sour beers separate from similar equipment used for regular beers.