Yes, it is possible. There are several ways to go about this task.
Here are a couple:
1. You could use a third party migration/integration tool that complies with the CRM SDK like Scribe (www.scribesoft.com)
2. You could write your own .NET application or build an SSIS package that uses web service tasks to perform the update. SSIS packages can use SQL Server Agent to schedule jobs and you can use many different methods to do this with a .NET application.
If writing your own you will need info from the SDK:
http://blogs.msdn.com/b/crm/archive/2008/05/07/integrating-crm-using-sql-integration-services-ssis.aspx
Software Specialist Crm