How to Thumbnail in Publisher Web Publications :
http://msmvps.com/blogs/dbartosik/pages/80553.aspx

And Reference for opening in a new window:
http://office.microsoft.com/en-us/publisher/HA011587451033.aspx
describes two methods. I found it easier to use the html method at first,
but eventually found the ECMAScript code approach more versatile, as I could
insert that hyperlink into a normal text box with other text.

And 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" in that
text box that you can just copy and paste other URLs into, and paste the
javascript into Publisher.

DavidF