[Mediawiki-l] Treating an external link like an internal link

[Ekompute .info]

Hi, I was wondering how to create a link to Dummipedia.org without typing
the full url as in [[Wikipedia:Main Page|Wikipedia]] and not [
http://en.wikipedia.org/wiki/Main_Page Wikipedia]. Which file do I tweak?
Looks like it is at DefaultSettings.php but I can't find the exact location
to add.

Assistance greatly appreciated.

PM Poon