you can gather the dataset from the application and push it to your report, in which case I write a xml of schema and data to speed the creation of the report, or you can call build the report using some sort of connection, odbc or ole and display the report from your application, this will bring up the CR parameter screen.
As for the stored proc, CR doesn't care if you display the parameters or not. Just tell it you want to use the stored proc, and it will create the parameters. You/your user will have to enter the dates to get the data, but CR doesn't force you to display parameters...they are just a means to an end.