your only options are to take COPA from lax or somehow get to iah and then take CO to panama city and then COPA southward.

either way, all flights on either airline will use aircraft configured with domestic FC seats. COPA's aircraft are identical to CO's as CO owns approx 49% of COPA (i think?).

best bet would be to get to LAX and go from there.

here are some pics of CO/COPA's FC

http://www.airliners.net/open.file/232663/M/
http://www.airliners.net/open.file/076188/M/