Peter,
Let us assume that the kind of documentation you are expecting is not available. Now, coming back to the business, are you still stuck somewhere in the process of installation ? If yes, then if you specify the particular step at which you got stuck, the people here might try to help.
Secondly, do you have an Apache server running, as yet ? I am a perfect newbie for apache/php/mysql/mediawiki myself. But first I made sure I have a running apache web server, where I can put HTML pages accessible to the world/intranet. Then I installed PHP and tested it to be working fine. MySQL was/is tricky for me and even now I am not very clear about creating databases/user privileges and so on. All I know how to assign a root password or create an account. Actually, PHPMyAdmin is my friend here. But, after all these I found installing Mediawiki was pretty straight forward .... or I should say, INTUITIVE. Yes, sometimes I got failure due to lack of permissions or version mismatch. I figured them out and upgraded my PHP. So, you must make sure you have an apache server running with functioning PHP and SQL support and you have a database user account with proper privileges.
Coming back again, where exactly you are stuck now ? What is the error message that you are getting ?
Regards, Suman.