Note that a new TBIT security checkpoint opened a month or two ago, mainly designed for transit PAX, it can be used by any with a same day BP ex LAX.
After the transpac morning arrivals are cleared, it tends to be very quiet from then on.
It is located on the lower level at the Southern end of the TBIT arrivals concourse.
More here (from the AA forum):
http://www.flyertalk.com/forum/ameri...l#post27013258