The best way would to add a PageList web control to the PageTemplate and a PageReference property to the PageType.
Then make a container that holds pages that redirects to the external links and poiint to that container to fill the PageList.
If you do it like this you can use features like permissions, startpublish and stoppublish on individual links (pages under the container).
Regards
HAXEN
Another solution is the Multipage property made by Intergen in New Zealand. This property allows you to build a list of links(both internal and external by using EPiServers Hyperlink dialog), which you then can render in your template.
The property can be downloaded from Coderesort: https://www.coderesort.com/p/epicode. Just apply for membership and then your ready. Let me know if you need more details about the property.
Good luck,
-Geir Allan Hove
Epinova