I'm sorry if this is obvious, but where can I find a list of airlines with whom Cathay Pacific has interline baggage agreements?

I'm planning to fly from Bangkok to Saipan in November. The most convenient trip is Bangkok-Hong Kong-Saipan. Hong Kong Express (now owned by Cathay) does the Hong Kong-Saipan leg. If Cathay has an interline baggage agreement with them, then I will book the Bangkok-Hong Kong leg with Cathay. I'd really like to avoid having to go through customs and immigration in Hong Kong. However, I can't find a way to book this trip on a single ticket.