Bearteacher, since I live in the US, I don't know about transit requirements from YVR to HKG through LAX. However, my sister had flown from SEA to HKG through LAX using AS -CX interline services several times. Here is her recent experience:

She was able to check through her luggage during the two most recent trips even though she held separate tickets for the SEA/LAX and LAX/HKG segments. She did not have to re-check her baggage at LAX, although she had to check in at the CX counter in LAX for her CX ticket from LAX to HKG.

In both occassions, her layovers at LAX were over 4 hours, but no problem from CX about stopover issues. My sister planned long layover at LAX because of AS' chronic problems on flight delays. She once missed a CX connection at LAX because the AS flight was late for more than 2 hours.

I hope somebody based at YVR or who is knowledgable to the Canada - USA - HKG transit problem can answer the technicality on clearing/rechcking luggage while transiting through LAX with a long stopover.

BW