whoops!!

I was going to say, maybe I should this with scan 
rules.  Like:

-*.gif +mywebserver.com/*.gif
-*.jpg +mywebserver.com/*.jpg

I just tested that and *yay* it works fine. The 
external links to the images are kept in tact and not 
modified (and not downloaded), which is what I wanted.

So I guess I just answered my own query :-)