Calypso is a largely improvised form. That makes it a bit different from ballads or Irish dance tunes. I've learned both improvised traditions (Middle Eastern) and not-very-improvised ones (Scottish and Hungarian) from people who could be described as tradition bearers. The non-improvised stuff is possible to get from recordings, though talking to a human makes it MUCH quicker. I don't think you can learn improvisation except first hand - the point of improvisational art forms is that they come out of frameworks that aren't always perceptible at all. What is *not* played is also part of the tradition.

The person who comes to mind as having gone to a foreign culture and learned enough about its music to perform at the highest level is the Irishman Ross Daly, who does Greek/Turkish music. It took him a long time.

If you're in a big multicultural city like London or New York there should be a practicing calypso performer or two around. If you're somewhere small with no native Trinidadians about, you probably don't have much option but to travel.