We use a little squirt (and turn down the pressure a bit, it doesn't bother me that the loo takes ages to fill), and rinse both pooey and wet nappies before 'damp-pailing'. (Drypailing really)

I only have a prewash on the longest cycle on my machine so I don't bother with one and very rarely have stains. When I do they tend to come straight out in the sun.