This was a lot easier a few years ago when B6 and AS were partners of EK, but it's a lot harder now that those partnerships have ended.
You're probably better off considering QR or SQ if you want a good experience from the US West Coast, and consider using an alternate airport (BUR, SNA, ONT) to connect at a different gateway as you probably won't be able to pick up a codeshare starting at LAX.