Custom Size input for Prestashop

it's an addon function on the Product page of Prestashop which enables the customer to choose in the Size dropdown box between predefined Size (example: size 36, 38, 40) or Custom Size. when customer selects Custom Size, a popup window should appear where the customer can input his own body measures in cm (example: hight, chest, waist, hip). the data/size entered by customer should be visible everywhere in the order processing (Shopping cart, order information, confirmation Email and so on). see attachment for clearification.