Thanks.

I'm going to work on it myself, and post it here if it works. But I'm not very knowledgeable about PHP, so if someone has it or comes up with it in the meantime that would be even better.
<added later>
Well, after perusing the code, it looks like this would involve some changes in the database. The key to what I want to do to make edited posts display the 'new post' icon. From what I can tell, the decision of which icon to display for various user input/activity is done with variables, and of course the contents of a variable resides in the db. Since I don't have access to my client's db, I'm not able to do it.
Oh well... less work for me.