Boiling for 30-35 mins in the best option, if you can fit it in a pot/pan. Dishwasher (pot/pan cycle, without detergent, of course) 1-3 times works wonders too. You can also fill a 5 gal bucket (assuming you need a bucket that big) with really hot water, and let the wood sit in it until the water stays clear for a couple days. Change the water out when it gets tea colored, and repeat the process. I have a piece of ghost wood that I soaked in a 5gal bucket for a week, then dishwasher, soaked for a week (still really tan water), dishwasher again, then has been soaking for about 4 weeks now. I change the water about every 3 days, and it's just now starting to stay clear.
This process also helps to sink the wood, so you don't have to weigh it down.