Prestashop automatic update of quantities and arrival date

I need a php script to automatically update my product stock quantities and arrival date from a .csv file. I will have a cron set for it to run every hour. I already have a script for this that run on 1.4.5 version (badly). I have now 1.5.4.1 of prestashop and it needs to work there. You can modify the ready script or build a new one. The csv file is downloaded from an url. The information will be updated in the database according to the product reference+supplier reference, not product id.