Encoding enc = new Encoding.Default;

SQLQuery.Queries.Clear(); // SQLQuery это и есть магический SQLDataSource
string sqlfile = Directory.GetCurrentDirectory() + "\\GetTasksForMegRegion.sql";
string tsql = File.ReadAllText(sqlfile, enc);

CustomSqlQuery MainQuery = new CustomSqlQuery();
MainQuery.Name = "MainQuery";
MainQuery.Sql = tsql;

QueryParameter p1 = new QueryParameter();
p1.Name = "@pDateStart";
p1.Value = edDateStart.EditValue;

QueryParameter p2 = new QueryParameter();
p2.Name = "@pDateEnd";
p2.Value = edDateEnd.EditValue;

MainQuery.Parameters.Add(p1);
MainQuery.Parameters.Add(p2);

SQLQuery.Queries.Add(MainQuery);
SQLQuery.Fill();

GridControl.DataSource = SQLQuery;
GridControl.DataMember = "MainQuery"