It would be a lot of (boring) work, but doable. But what if your blog has hundreds of users, and not all of them are as tech-savvy as you are? This is the question someone on the Six Apart ProNet mailing list recentlly asked.
A lot of discussion followed, until Jun Kaneko (Six Apart's MT Community Manager) pointed out this little gem of a plugin from Japan: EntryPrefsFixer. (Japanese blog entry about it here). I haven't tested it yet, but a quick look at the code seems to indicate it should work for MT4 and MT5 (and has both English and Japanese text).