FIFO Cost --Mass Updation

Dear All,

We using cost method is "FIFO" and now we need to update item cost for all items through API or Open interface and we very well know an have option in application form level in Cost management module.Because we have more than 50000 items .Since its not possible to do the same in form level one by one.

Let me know how to do the mass update without form level for this "FIFO" cost method.

Please help me.