victor,
TACA does not have a cadet pilot scheme, so that means that you would have to arrange for and finance your own pilot training by the usual method and end-up with a Commercial Multi-IFR licence. Then start applying to them, at their address in San Salvador.
It seems like TACA has been forced to drive down it's minimum qualifications, something that I (an outsider) forsee continueing. Last I heard they are hiring at 500 hours Total Time. Unfortunately, as a Salvadoran, there are no local regional airlines operating so that you can build time, however, there are plenty of opportunities in the United States, where I assume you have the legal right to work.
However, if you become employed at a regional airline in the United States you may want to consider the pros and cons of employment at TACA, considering that they supposedly now force new-hires to sign a 15-year bond. Fifteen years is a very very long time.
If you do want to work for TACA and you do travel to Central America sometime in the future on TACA, ask if you can see the flight deck crew either before or after the flight (visits during the flight are unfortunately prohibited). Mention your interest in aviation, and if your chat goes well with one of the pilots ask him he you can contact him in the future for advice as you work advance in your career. Most pilots are happy to give some advice to someone starting out.