In St Martin head down to Orient Bay and speak to the guys at the CNS Centre. There is another location that is super sweet, but speak to the guys and they can direct you.
In Barbados head down to Silver Sands area. If your just there for the day make your way down to Brian 'Action Man' Talmas centre at Silver Rock. Super nice conditions over there.
In St Lucia if your coming by cruise line head North to Cas em Bas. There should be a load (3) local kiters up there if its windy and were not on our travels.
For more locations check out the video on my site of the Cabrinha Trip: http://www.davidhastilow.com/cabtour2006.mov
If you need any more info then pm me. I live in St Lucia but travel the islands.