I think you're right that US websites are fairly limited for this search...the best I could come up with was on SQ's website, a mileage-earning fare HKG-SIN-SYD-SIN-HKG for HK$6612 (US$847), 11,010 status miles. SYD wouldn't be the worst place you could go for a weekend in October.

I would suspect you could find a better deal on some * carrier out of HKG using Asia-based sites...perhaps someone with more experience in HKG-based MRs will post some.