I found the interface is fairly self-explanatory. The only problem is that I can never get options dialogs to work right, so you have to edit the backup-delay by editing the script itself. But I think this is fairly easy to see, so I think it'll be okay. Comment if you have any questions.
entrykeep.user.js
You'll need FireFox or Mozilla (I have it working in Moz, can't guarantee that you can too) and the Greasemonkey extension.
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greasemonkies. 