Forecast Overrides

Hi,

We do have a situation where we need to override the forecast. As the items are new, we did load the sales history in the Sales Data table. We dont have the forecast/future records in the sales data table to override the forecast. Is there a easy way to create those records to override/load the forecast. We do understand that we will have an opportunity to override once the engine generates the forecast. But we need to perform the overrides ASAP. Thank you.