When I am using eels I will buy them up to a week early. I, and a friend made a bucket for them and even in the summer heat I can keep a few dozen for a week easy!!
Just put your eels in it with some seaweed, put the basket in the top with ice. Keep in shade or cool basement, garage.
The Ice will melt and give the eels a cold shower, keeping them cold, wet and happy!!
You can see how to make the bucket in the "how to" section here
http://www.striped-bass.com/Stripert...1&page=1&pp=20