Currently, forward mapping is available for CUD operations of stored procedures. Now, you cannot forward map a stored procedure that returns a result. With the new Visual Designer context you can call ExecuteStoredProcedure and have your procedure run but this is not the mapping you require. The feature you desire will be available at some point after the Q2 release. You can expect to see a dedicated UI to forward map stored procedures.
As to your next questions, the Classic Wizards are not open source. You can always find information on working with the old wizards in our online documentation. But I am not sure as to exactly what you are trying to achieve, you will not be able to modify our product. However, you can request a feature and we might consider it for introduction in some of our next versions.
If you have any further questions, please do not hesitate to contact us.
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