Below is the snippet that shows how to create ISDataSource at runtime.

protected void Page_Load(object sender, EventArgs e)
{
    ISDataSource isds = new ISDataSource();
    isds.ID = "ISDataSource1";
    isds.SchemaName = "dsNorthwind_ReadOnly";
    isds.SchemaType = ISNet.WebUI.DataSource.SchemaType.DataSet;

    ISDataSourceTable ShippersTable = new ISDataSourceTable();
    ShippersTable.TableName = "Shippers";
    ShippersTable.SelectMethod = "GetData";

    isds.Tables.Add(ShippersTable);
    isds.Tables[0].TypeName = "dsNorthwind_ReadOnlyTableAdapters.ShippersTableAdapter";

    Page.Controls.Add(isds);
}

Hope this helps.