Assuming you are adding it to an already hopped partial boil - adding it right at the end of the boil is fine. Mix it well and let it sit for 10 minutes to sanitize - like dbsmith says better to be on the safe side.
Boiling it is fine, too....mix well and careful not to scorch.
Civilization begins with Beer !
Primary: nothing in the pipeline at the moment
Secondary: some summer beers are imperative
Bottled: Nut Brown, Listermann's Cream Ale, American Pale Ale, Holiday Ale, HopNog, Honey Malt Cream Ale, Irish Stout, English Brown Ale, BIAB English Ale, India Black Ale, Bengal Juice, BIAB Cherry Wheat on the cherries, Belgian Pale Ale, Island Hefe on Mango, Island Hefe on Apricot (and dang -these are awesome beers)
Next Up: Hop farming