I pretty much keep them the way Heika does however my gutload is a bit different ...
1 softboiled egg, honey, molasses (spelling?), baby rice cereal, gutload and plain yogurt.
I mix it into a paste and smear it on the side of the container they are in. Fridge the rest.
Yeah, as mentioned - dont feed the larva anything. It will take longer for them to pupate if you do.
I also slow them down in the fridge. If you forget about them in the freezer then you are screwed.
-roo