sidex100

Для потомков:
движок установлен в document_root/wiki/

.htaccess:

DirectoryIndex /wiki/index.php

RewriteEngine On
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-f
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-d
RewriteRule ^(.*)$ %{DOCUMENT_ROOT}/wiki/index.php [L]

RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-f
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-d
RewriteRule ^/?wiki/images/thumb/[0-9a-f]/[0-9a-f][0-9a-f]/([^/]+)/([0-9]+)px-.*$ %{DOCUMENT_ROOT}/wiki/thumb.php?f=$1&width=$2 [L,QSA,B]

RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-f
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-d
RewriteRule ^/?wiki/images/thumb/archive/[0-9a-f]/[0-9a-f][0-9a-f]/([^/]+)/([0-9]+)px-.*$ %{DOCUMENT_ROOT}/wiki/thumb.php?f=$1&width=$2&archived=1 [L,QSA,B]

document_root/wiki/LocalSettings.php:

$wgScriptPath = "/wiki";
$wgScriptExtension = ".php";
$wgArticlePath = "/$1";
$wgEnableUploads  = true;
$wgGenerateThumbnailOnParse = false;

Сделано в плагине Redwerks.
Еще раз спасибо Abcd_Efgh!