You should be eligible to use this functionality.
According to eBay FAQ:
STP (Strike-Through Pricing) feature is available to qualified sellers who participate in the Discount Pricing program. Once qualified, sellers can apply Discount Pricing to both MSKU and Non-MSKU items. STP is available on the US, UK, DE, FR, IT, ES sites while MAP is available only on the US site. This program requires every merchant to go through the vetting process, and We cannot enable the STP and MAP to customers without going through the process. However, for this particular issue, it would be best for you to contact our end user customer support team who have the appropriate tools and access to help you:
Please visit : http://contact.ebay.com/ws/eBayISAPI.dll?ContactCS