Here is what I have gathered-- no guarantees on acuracy though.
You need to be a citizen (permanent resident?) of either one of the countries that Grupo TACA is a part of. Namely Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica or Peru. Applications are taken (resume with passport sized photograph) at any one of the local offices.
From what I've gained from TACA pilots, the contract and conditions depend on the silo that you are a part of. The situation for LACSA (Costa Rican) pilots is different for that of the El Salvadoran group.
According to one First Officer I recently chatted to (January) the requirements fall in the range of a US ATP, with about 1200 total time (obviously a discrepancy).
Hope this helps somewhat. You really should head down to your regional TACA office to talk with the HR person there.