This is a method I used at one time.

Mix baking soda and vinegar. Do not allow prey to come in contact with this mix, as it will make them stink.... if they do have some smell to them afterwards, you can let the "air out" for a short time. Somewhere in the archives, I have a post on using this method and it has a link that will show you how to make a chamber for this type of use.

Got to run to the dr. But when I get back I will see if I can find it again.