No I don't think you can make Yahoo mail save your message every 3 minutes. Why do you need to save every 3 minutes, are you like writing an essay to somebody? However, you can always save manually by clicking the "Save as Draft" button while typing your message. If you are afraid of losing a really long message, type it on a Word document first and then copy and paste the message, that is the only safe way to do it. I think they didn't make an autosave function because everytime you save, it will have to send something to the server and refreshes the page to indicate that you've saved your message, which gets annoying when you're trying to type a message.
When you save something on the internet, a signal will have to be sent to the server, not like saving something on your computer, which can be done instantaneously.
