Just a word of warning- it's only a couple drops of the liquid detergent, other wise you end up with a bigger, sudsy mess than you started with! (yep, learned that one the hard way...)
This is the same basic recipe that was posted here earlier this year. This is the version that I used with good results:
1 cup Hydrogen Peroxide
1 tablespoon baking soda
1 drop liquid hand soap