I've been in your shoes before! It's quite frustrating.
SYD-HNL return varies in miles and points between Jetstar and Qantas. If you can get direct flights with Jetstar alone, then you're looking at handing over 57,600 points +$411 in fees (with only 20kg checked bag each way) on the Qantas Frequent Flyer (QFF) website.
If you can get direct flights with Qantas to HNL, you're looking at handing over 72,000 points + $521 in fees (although you'll get 2 x 23kg baggage allowance).
If you go for a mix of Jetstar/Qantas, or if you have to take flights via Melb/Brisbane first, those points and fees will change slightly, but will be within those limits above.
Generally, to use Qantas points with any other airlines, you'll need to redeem more points (and sometimes a lot more), than you do with Qantas. On routes that Qantas/Jetstar flies, it's just not economical to use Qantas points.
In this case, I'm not sure if any of Qantas' partners actually fly the SYD-HNL route, so you don't have many options.
You might find that depending on the time of year you want to travel, the cost of a full price returns tickets to HNL is above $1,000 (with Jetstar) and even higher with Qantas. If awards are available at this time, then it could be worthwhile using the points.
However, in my opinion, if you're able to get a cheap sale fare with Jetstar (sometimes as low as $600 return), you'd be much better holding on to your Qantas points, accumulating more and redeeming for a business class flight to Asia!
Let me know if my response throws up more questions for you!