I'm sure you've already seen
this, but in case you haven't...
I'm thinking that you can use the custom keys/value settings. Here are my thoughts: In template-functions-post.php add this:
Code:
?php the_content('Read More...<img src="<?php echo $hotlink ?>"
alt="read more" title="Read More..." />'); ?
In the custom fields, have the key be hotlink and the value be the name of your image. I've got NO idea if this would work, but it could. :shrugs:
edit: my php statement may be off.
It's always trial and error with this stuff for me.