I can't see why not (subject to them reissuing your AONEx's - at a fee) as advised by alect, but you might get some puzzled questions from CX as to why you wanted to do this. You'd also have to make sure your bags get checked all the way through - and there may be an issue with them being offloaded in YVR and then reloaded, so "connect times" might be important. And if they don't issue the YVR-HKG BP in JFK, then that's another minefield (forcing you off the plane in YVR).

I can't see any reason why you wouldn't be able to ask CX this question; i.e. it's effectively just inserting an extra segment into your ticket, so providing your itin is still valid (i.e. you have a spare segment, and you aren't already doing a US trans-con), then it should be OK. Caveat: I haven't read all the OWE rules, and I am not an expert on them! Do let us know how you get on.