Satellite use theft by terrorists? Explain this to me again

As set out here, an organization recognized as "terrorist" has been tapping into Intel satellite 12. Now, here is a report on Intelsat's intended shutdown of that "unauthorized" use:

The Liberation Tigers of Tamil Eelam ... which the U.S. State Department lists as a foreign terrorist organization -- are pirates who have been using the Intelsat 12 satellite for illegal radio transmissions, the satellite company said in a prepared statement.

There have been various reports in the Asian press about the terrorist group's recent use of the Intelsat satellite to transmit its official radio broadcast, Voice of Tigers.

I must confess that I am not a tech whiz, but exactly how can you tap into a satellite like that? Aren't there secret codes or something?

UPDATE: Some background on the LTTE here.

UPDATE2: LTTE say use is "legitimate" as set out here.