Passing parameters using SQL to Webi report

Question

I am using Webi to create reports but instead of using universes I would like to use custom SQL queries since I already have stored procedures created. In the stored procedures I have parameters like @date and @id. Is there a way to use them in Webi custom SQL scripts?

An example is:

SELECT
   Client,
   TradeSize 
FROM
   table1
WHERE Date = @Date
  AND id = @ID