There have been a couple of other threads about exchanges to Hawaii.
http://www.disboards.com/showthread.php?t=1307088&referrerid=&highlight=hawaii
http://www.disboards.com/showthread.php?t=1297226&referrerid=&highlight=hawaii
Availability is difficult during the high seasons, and most people need to put requests in at least a year in advance and sometimes two years in advance.
My advice if you have certain dates you need is to rent a place where you want to stay. Instead of dealing with the uncertainty of a trade and varying dates, you can get the resort and dates you want, and book your flights accordingly. Exchanging into Maui during off-season is do-able, but you still need to be flexible with your dates.
There are timeshare owners in Hawaii who might like to trade a week for a week at
DVC, so that might be a possibility. Or, you can rent your DVC points out to pay cash for a Hawaii reservation. One thing to keep in mind is that if II requires 160 DVC points for a 1 bedroom unit in Maui/Hawaii, you can't always expect to only pay your computed DVC "rental value" (160 x $10-$13) for such a unit, especially during high season. Prices vary by island, but Maui is often more expensive than Kauai or the Big Island. Studios are easier to exchange into and find.
We own on Maui because it is a difficult trade. We own DVC points for the same reason. It is hard to plan a vacation for four with airfare and school holidays and play the exchange waiting game. Too nerve-wracking for my sanity.
There are lots of Hawaii rentals on craigslist, redweek, TUG and myresortnetwork, for example. Good luck! Feel free to pm me if you have any questions about Maui.