I use a mixture of nice thick flannel contours (inside, against me), with thick flannel prefolds folded into thirds lengthwise and used as "soakers" (in the middle) and thin flannel contours on the outside (to hold them all in place and pin).
I wash mine pretty much the same way as PooBrat does his (see below).
First, if they've been in the diaper pail for a few days and are really good and smelly, I put them through a rinse cycle.
Then I wash them using liquid Dreft, and sometimes a tiny bit of OxyClean.
After that, I do another wash cycle with about 1/4 cup of white vinegar. Then one more rinse cycle.
After that, I put them in the dryer but don't dry them all the way. With them still slightly damp I spread them out on the floor in the closet (or on the guest room bed if my kids are not at home) and let them air dry the rest of the way.
I usually wash my plastic panties while in the shower, by hand, using liquid hand soap. I then rinse them off and hang them up over a towel and let them air dry.