Reference:
http://office.microsoft.com/en-us/publisher/HA011587451033.aspx
describes two methods. I would expect that you can use the ECMAScript code
approach with hotspot hyperlinks.

If you choose to use the ECMAScript code approach note that the first
javascript code snippet is incorrect on the website. Use this instead:

<script language="JavaScript" type="text/javascript">function Show(Url,
Name, Features) { window.open(Url, Name, Features); }</script>

I write the hyperlink code snippet that I am going to insert as plain text
in a separate text box that I drag off into the scratch area just for that
purpose. Then you can just copy and paste the code snippet from that text
box when you insert the code in the hyperlink address field (use Ctrl + V).
Once you get one link to work correctly, then you have a "template" of the
code in that text box that you can just copy and paste other URLs into, and
paste the javascript into Publisher.

DavidF