Passing Stored Procedure between CR XI and SQL Server 2005

[report2000]

I have a stored procedure that is resides in SQL Server 2005.
**Bring back all results for multiple firms
EXEC dbo.USP_RPT_BOB_CONTRACT @Firm_ID_MULTI = '2888, 18458, 21505, 2842, 13254'

Now I used the CR XI to link the reprot to Stored procedure (using command box).

Now I need to let user to type lets say , ('2888, 18458) and bring back only those two sets of records. Pass the parameter back to SQL Stored procedure and return only ('2888, 18458)

Do not want to bring everything in and then filter it in CR XI. It takes too much time.

Any suggestion?

Thank you