How do you call a Stored Procedure in SSIS?

I am trying to create an SSIS package that queries data from a table, and calls a stored procedure in another database with each row.

In my old DTS package, I was doing this:

EXEC myStoredProcedure ?, ?, ?

...and then I mapped the parameters. However, in SSIS, I can't figure out how to make this work.

I have a Data Flow task, which first runs a query for the data. It passes the data to an OLE DB Destination. I set the Data access mode to "SQL command", but when I try to put in the SQL above, I get "Invalid Parameter Count" when it parses the SQL. I can't get to the Mappings screen. Any ideas?