You'd have to manually edit the html file that MT generates, and create addition html files for each image in your series.
Here's the source of one of my popup images:
CODE
<html>
<body topmargin="0" leftmargin="0" marginheight="0" marginwidth="0">
<img src="http://kadyellebee.com/mt/past/invite-cover.jpg" width="300" height="265" border="0">
</body>
</html>
So if I wanted that popup to show the next image in the sequence, I'd change it like this:
CODE
<html>
<body topmargin="0" leftmargin="0" marginheight="0" marginwidth="0">
<a href="http://kadyellebee.com/mt/past/invite-inside.html"><img src="http://kadyellebee.com/mt/past/invite-cover.jpg" width="300" height="265" border="0"></a>
</body>
</html>
Then create a invite-inside.html file that had similar code in it depending on whether it was the last one or if another image was after it in the series.
Does that help?
Kristine