Yes you can upgrade from coach in any fare bucket to business with LANpass kms
You need 36,000 to upgrade from EZE to LIM and 50,000 to upgrade LIM to LAX. I believe these are to upgrade RT. If you are already in EZE and want to upgrade the retur segment to LAX you will have to call LAN and ask them if they will do one way upgrades for half the kms
http://www.lan.com/es_co/sitio_perso...a_premios.html