How to migrate WordPress Blogs into Multisite without using the GUI-Import/Export Feature

I’d like to migrate some quite huge WordPress-Blogs into one Multisite Installation.

The Export-Wizard and the Import Wizard are bound to PHP-Limits (Memory, Execution-Time) and so the Export and Import often fails.

There must be a way to do it by hand (only using MySQL and or the command line).

Importing a single WP blog to a WPMu Installation

http://sillybean.net/wordpress/migrating-single-wordpress-installations-into-multisite-networks/