You should have used mod_mls_checklist.
This one lists all the steps the user has to do.
But you can run this query:
INSERT INTO `jos_mls_events_participants` (`id`,`eventid`,`userid`,`subscribed`,`subscribed_time`,`paid`,`paid_time`) VALUES ('','X',(SELECT `id` FROM `jos_users`),'1',NOW(),'1', NOW())
PLEASE make a backup of your database before you run this query
And your table prefix might be different than jos_, and replace the "X" with your eventid.
... let me know if this really works
