RewriteEngine On

RewriteCond %{HTTP_HOST} .*yourdomain.com
RewriteRule ^/forums/((urllist|sitemap_).*\.(xml|txt)(\.gz)?)$ /forums/vbseo_sitemap/vbseo_getsitemap.php?sitemap=$1 [L]

RewriteCond %{HTTP_HOST} .*yourdomain.com
RewriteCond %{REQUEST_URI} !/forums/(admincp/|modcp/|cron)
RewriteRule ^/forums/((archive/)?(.*\.php(/.*)?))$ /forums/vbseo.php?vbseourl=$1 [L,QSA]

RewriteCond %{HTTP_HOST} .*yourdomain.com
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !^/forums/(admincp|modcp|clientscript|cpstyles|images)/
RewriteRule ^/forums/(.+)$ /forums/vbseo.php?vbseourl=$1 [L,QSA]