For future reference:
I met a nice young British couple and we both went through domestic side security. When we were "almost" at the gate, we walked into a locked glass door and our gate was just on the other side. So, we figured this was treated as an international flight. We walked all the way back and to the other side of the airport. Went through security again, stood in line for passport control. I invited them over to the AC and/or the LAN club. Finally it was my turn for passport control. Went up, the immigration officer looked at my passport and BP, put a little mark on my entry form and informed me that I wasn't really leaving the country so nothing to worry about. He wished me a safe trip. I get to the Duty Free area and wait for the young couple who were right behind me. After 15 or so minutes I gave up as they were not coming. Walked over to the AC, had a drink, but the curiosity got better of me and decided to find out what happened. Left my luggage and walked over to the gate and sure enough, they were on the other side of the door with about 100 more passengers.
Walked back to the AC and asked what happened.
Here is the explanation:
Anybody flying in J or having status with LAN or OW or a member of AC and flying to IPC can come through the international side as that's where the clubs are located and the immigration officers will know and let you through.
The "unwashed"
have to go through the domestic side and wait until boarding time when the LAN agent will open the door and let you board.
Sure enough when boarding started, the door was open for the passengers on the other side with security keeping an eye that they walk right to the jetway which is the first gate.
Hope this helps future IPC visitors.