Index: wp-config.php
===================================================================
--- wp-config.php
+++ wp-config.php
@@ -8,6 +8,10 @@
 // You can have multiple installations in one database if you give each a unique prefix
 $table_prefix  = 'wp_';   // Only numbers, letters, and underscores please!
 
+// Uncomment the following to set a shared user and usermeta table.
+//define('CUSTOM_USER_TABLE', 'users');
+//define('CUSTOM_USER_META_TABLE', 'usermeta');
+
 // Change this to localize WordPress.  A corresponding MO file for the
 // chosen language must be installed to wp-includes/languages.
 // For example, install de.mo to wp-includes/languages and set WPLANG to 'de'