Action points, or Hero Points, or some similar mechanic is good, from a mechanical perspective. I don't know that I have any other specific mechanics advice in mind, except to review all the various skill descriptions and give some thought about how to apply skill checks to whatever "swashbuckly" action folks dream up to try.
As for general GMing tricks and tips, I ran a game not long ago where the stated goal was to be "swashbuckly" but it didn't always turn out that way. Too much ingrained habits on how D&D was to be played, I think. To try and change that (and it worked marvelously well, I might add) I spent some thought before the session thinking of exotic locations in which to stage fights, where the environment could come into play. That, and having NPC opponents who were attempting all kinds of swashbuckly maneuvers really got the players into the spirit of things, and before long they were matching them buckle for buckle.
For inspiration, I suggest watching The Three Musketeers (Michael York and Raquel Welch version, done in the 70s), Captain Blood (Errol Flynn's first blockbuster, and the movie that made him a star, done in 1935 and just recently released on DVD) and the older Zorro movie; the one with Tyrone Power, also done (I believe) in the 1930s.
You could also read some Rafael Sabatini, author of the novel on which Captain Blood was based. His other really good novels are, IMO, The Black Swan, St. Martin's Summer, and Scaramouche. A lot of his novels are public domain now too--I believe all of those (except The Black Swan, sadly) are available as txt files on Project Gutenburg.
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