I'm sure there a several ways of dealing with this. Support can probably give you a better answer than I can.
We run the VisualCron service as a specific user. ie right click on the VisualCron service, choose the log on tab, click the 'This account' radio button, and enter the user you want to run the service with. Then you can give this user the appropriate rights in yor database. I'm not saying this is the best way of doing it, it's just one way.
Thomas