Read up on SECONDARY USERS and that should solve your problem. Without secondary users, it can't be done as a single computer can only be associated with a single LMI account.
(DISCLAIMER: I am NOT an employee of LMI, nor do I have any financial concern in LMI. I am strictly a HAPPY USER of LMI products. I am using PC version and XP SP2. Other systems or versions may act different than described above.)