[wp-hackers] Inserting More Tags Across Entire Database

[Dan Fellars]

I'm migrating a decent size database (50k+) of articles over to wp and I
want them all to have a <!-- more --> tag inserted after a specified X
number of characters.  Obviously would prefer not doing it manually.

Any ideas on how to approach it, or any code lying around that does it?
The tricky part is handling the html so that I don't insert the more tag
in the middle of an html tag.