The dishwasher might work, but I really don't know what temp it gets to and I'd rather control things myself. I recently pasteurized a batch of cider on my stove top.
- Fill a deep pot with water halfway and heat water to about 180-190
- Put a kitchen towel in bottom of the pot as a buffer between the pot bottom and bottles
- Place bottles into the hot water (the temp will go way down to 130-140 but keep the heat on high and it will slowly come back up to temperature
- Put a lid on the pot to retain heat
- When the water gets to 160, lower the heat.
- You don't need to go any longer than 10 minutes. The internal temp of the bottles should get to 150 in 5-7 minutes. Yeast will die shortly after
I'm going to make some cream soda soon with the same process. When I bottle, I'll use glass and at least one platic bottle. I can monitor carbonation by squeezing the plastic bottle. When it's really firm, I know it's time to pasteurize the glass bottles and lock in carbonation safely.