If you put these two lines in to an .sql file and run the query, it will enable the mercs.
CHANGE NAME OF DB 'peq' to what yours is.
Code:
UPDATE `peq`.`rule_values` SET `rule_value`='true' WHERE `rule_name`='Mercs:AllowMercs';
UPDATE `peq`.`npc_types` SET `class`='71' WHERE `lastname` LIKE '%Mercenary Liaison';