This is kind of a two part question. The first part being how to access data in another database, and the second part being how to schedule the procedure to run each week.
Part 1. In order to access data in another database you have to use the three part name of the object. With that format being Database.Owner.Object. So if you were going to create a procedure which truncated a table and then loaded in all the data from a table in another database it would look like this.
CREATE PROCEDURE YourProcedure AS
TRUNCATE TABLE YourTable
INSERT INTO YourTable
Part 2. In order to schedule the procedure to run each week you will want to use the the SQL Server Agent to schedule the job. In the User Interface navigate to the SQL Agent (in SQL 2000 it’s under management, in SQL 2005 it’s directly under the server). Right click on Jobs and select new job. Put the stored procedure name on the job step, and setup the schedule to run once per week.