Changing a user's password

Does anybody know if it is possible, using database security in Siebel, to change a user's password via a business service or script?  If so, can you give a brief example on how to do it?  We are trying to implement a user lockout functionality when a user has not used the application for a specific period of time.  I have read that the only way to easily accomplish this is to change the login password because removing and trying to save all of the user's responsibilities is not feasible for us and simply changing the the userid's status has