BuddyPress.org

Thanks Paul, I made it :), it’s something really rough, but if somebody needs it here it is:

<?php

// parametri del database
$db_host = "localhost";         //Your database host
$db_user = "database";          //Your database username
$db_password = "password";      //Your database password
$db_name = "database_01";       //Your database name

$db = mysql_connect($db_host, $db_user, $db_password);
set_time_limit(0);

if ($db == FALSE)
die ("Connection Error.");

mysql_select_db($db_name, $db)
or die ("Database Error.");

$n = 0;
$query = "SELECT * FROM <code>wp_posts</code> WHERE post_type = 'topic' OR post_type = 'reply' ORDER BY post_date ASC";

$result = mysql_query($query, $db);

while ($row = mysql_fetch_array($result))

	{
		unset($user_id);
		unset($reg);
		unset($guid);
		unset($id);
		unset($post_parent);
		unset($post_date);
		unset($nicename);
		unset($displayname);
		unset($title);
		unset($forum);
		unset($forumurl);
		unset($post_type);
		unset($forum_id);
		unset($acttype);
	
		$user_id = $row['post_author'];
		$guid = $row['guid'];
		$reg = $row['user_registered'];
		$id = $row['ID'];
		$post_parent = $row['post_parent'];
		$post_date = $row['post_date'];
		$title = $row['post_title'];
		$content = $row['post_content'];
		$post_type = $row['post_type'];
		$forum_id = $post_parent;
		
		$q1 = "SELECT * FROM <code>wp_users</code> WHERE ID = '$user_id'";
		$r1 = mysql_query($q1, $db);
		$e1 = mysql_fetch_array($r1);
		
		$nicename = $e1['user_nicename'];
		$displayname = $e1['display_name'];
		
		if ( $post_type == 'reply' ) {
			$q1 = "SELECT * FROM <code>wp_posts</code> WHERE ID = '$post_parent'";
			$r1 = mysql_query($q1, $db);
			$e1 = mysql_fetch_array($r1);
			
			$post_parent = $e1['post_parent'];
			$title = $e1['post_title'];
			$guid = $e1['guid'];
		}
		
		$q1 = "SELECT * FROM <code>wp_posts</code> WHERE ID = '$forum_id'";
		$r1 = mysql_query($q1, $db);
		$e1 = mysql_fetch_array($r1);
		
		$forum = $e1['post_title'];
		$forumurl = $e1['guid'];

		if ( $post_type == 'topic' ) {
			$action = mysql_real_escape_string('<a href="http://www.yoursite.com/users/' . $nicename . '/" rel="nofollow">' . $displayname . '</a> ha iniziato la discussione <a href="' . $guid . '">' . $title . '</a> nel forum <a href="' . $forumurl . '">' . $forum . '</a>');
			$acttype = 'bbp_topic_create';
		} else {
			$action = mysql_real_escape_string('<a href="http://www.yoursite.com/users/' . $nicename . '/" rel="nofollow">' . $displayname . '</a> ha risposto alla discussione <a href="' . $guid . '">' . $title . '</a> nel forum <a href="' . $forumurl . '">' . $forum . '</a>');
			$acttype = 'bbp_reply_create';
		}
		
		$content = mysql_real_escape_string( $content );

		if ( $user_id > 0 ) {
			$q1 = "SELECT COUNT(umeta_id) AS conto FROM <code>wp_usermeta</code> WHERE user_id = '$user_id' AND meta_key = 'last_activity'";
			$r1 = mysql_query($q1, $db);
			$e1 = mysql_fetch_array($r1);
			
			if ( $e1['conto'] > 0 ) {
				$q = "UPDATE wp_usermeta SET meta_value = '$post_date' WHERE user_id = '$user_id' AND meta_key = 'last_activity'";
				mysql_query($q, $db);
			} else {
				$q = "INSERT INTO <code>wp_usermeta</code> (<code>umeta_id</code>, <code>user_id</code>, <code>meta_key</code>, <code>meta_value</code> ) VALUES ( NULL, '$user_id', 'last_activity', '$post_date' );";
				mysql_query($q, $db);
			}
		}
		
		$q = "INSERT INTO <code>wp_bp_activity</code> (<code>id</code>, <code>user_id</code>, <code>component</code>, <code>type</code>, <code>action</code>, <code>content</code>, <code>primary_link</code>, <code>item_id</code>, <code>secondary_item_id</code>, <code>date_recorded</code>, <code>hide_sitewide</code>, <code>mptt_left</code>, <code>mptt_right</code>, <code>is_spam</code> ) VALUES ";
		$q .= "(NULL, '$user_id', 'bbpress', '$acttype', '$action', '$content', '$guid', '$id', '$post_parent', '$post_date', '0', '0', '0', '0')";
		mysql_query($q, $db);

                $n++;
	}

mysql_close($db);

echo "Done! inserted $n activity entries";
?>

The action is in italian, you can modify as you want