Ok I found it, did it but I've made some tests and it doesn't work...
                          
                          http://msurowiecki.netau....x.php/guestbook/entry/add - link to my site...
                          
                          The file to edit is: components/com_easybook/controllers/entry.php
                          and the code to paste is:
                          
                          
                          
                            /*
                             * ADD NiK START
                             * We load the plugin group 'easy' and define an event 'onSubmitEasyBook'
                             */
                                       
                            //--Easy plugins
                            JPluginHelper::importPlugin('easy');
                                       
                            //--Get reference to dispatcher
                            $dispatcher =& JDispatcher::getInstance();
                                           
                            //--Custom handlers
                            $results = $dispatcher->trigger('onSubmitEasyBook', array(&$admins, &$temp));
                               
                            foreach( $results as $result )
                            {
                               if( JError::isError($result) )
                               {
                                  //--A plugin returned an error - hopefully it has displayed some message cause..
                                  //--We will end here
                                  return false;
                               }
                            }//foreach
                            
                            /*
                             * ADD NiK END
                             */
                          
                          Why it doesn't work? I did everything like you showed. Should I see numbers and letters to enter when signing my guestbook?