Originally Posted by
PV_Premier
Not sure but probably not since LAS and LAX are not coterminals. Never hurts to ask, but be prepared to be told no.
Best case might be to book JFK-SEA-LAX-(stop)-HKG and buy a round trip LAX-LAS, which should be completely doable.
The purpose of the AS leg is to get you to the gateway city and not a side trip so I'd expect denial.