I wash the accident pants in the washer by themselves too. I put them in a diaper pail type thing, with a lid to control stench in the house. I always rinse the pooh out in the toilet. Then I start the wash load and add the detergent. Then I add a lot of vinegar or bleach. The bleach really works best but if I am out I will use the vinegar. It works usually. On the odd occasion I will run the washer a second time through the whole cycle.
We only have clothes in this instance, I would not use training pants, the floor and other stuff is just too much to add in to the mix. I have other things to do besides laundry...anyway. Once they have been dried they should smell fresh and clean. Like I said, bleach always works and when I am out I use the vinegar but when I use the vinegar I often have to run them a second time around.