Shake, strain, up, garnish.
There are all sorts of recipes for this one online; this is Sam Ross'. Many recipes call generically for aged rum, rather than Jamaica(n). Others, notably cocktaildb's, call for falernum and a touch of sugar to offset the lime: http://www.cocktaildb.com/recipe_detail?id=426 . The constants are some sort of dark rum, lime, sugar, and bitters.
Crosby Gaige's Cocktail Guide, via Sam Ross' Bartender's Choice app for iOS.