Installation instructions are for the modification itself and not for installing the mediawiki. First you have to learn howto install the mediawiki and get your things together (
http://www.mediawiki.org/wiki/Manual...ling_MediaWiki ) . After that, you are able to install the mod as it is described here.
Just for a hint (that worked for me): Install the wiki within your document path where vbulletin 4 is installed so you can call it by http:// my name of my page/mediawiki . That will make it easier to get the vbulletin integration later.
Don't blame bepe's work for not being able to get the basics to run by yourselves!
cu
Gargi