ergophobe - 5:48 am on Apr 24, 2011 (gmt 0)
Is the built-in revisions system inadequate?
You should have a "Revisions" rubric at the bottom of every post if it has more than one revision. Click on the bar and it expands to show all past revisions.
It seems like the easiest thing to do would be to whip up a screencast of how to restore a revision and have the client load that video on his computer or bookmark the YouTube url or whatever.