Index: capabilities.php
===================================================================
--- capabilities.php	(revision 10220)
+++ capabilities.php	(working copy)
@@ -501,7 +501,11 @@
 	 */
 	function _init_caps() {
 		global $wpdb;
-		$this->cap_key = $wpdb->prefix . 'capabilities';
+		if ( defined('CUSTOM_CAPABILITIES_PREFIX') ) {
+			$this->cap_key = CUSTOM_CAPABILITIES_PREFIX . 'capabilities';
+		} else {
+			$this->cap_key = $wpdb->prefix . 'capabilities';
+		}
 		$this->caps = &$this->{$this->cap_key};
 		if ( ! is_array( $this->caps ) )
 			$this->caps = array();