amazon bulk upload via .txt file ~ how to override preset field values

need someone who is familiar with amazon product bulk upload via .txt file to show me how to override preset field value of amazon seller central. for example, under collectible coins, your can only choose limited amount of countries under country of origin. i need to add countries that are not included in the selection. please provide solutions such as this page http://www.amazon.com/1943-Ireland-Half-Penny-Coin/dp/B005JQIEFI/ref=sr_1_1?s=coins&ie=UTF8&qid=1457565249&sr=1-1&keywords=ireland+penny will pay $50 for the right solution