如何在Joomla中自定义Last-Modified Header？

Even in the latest Joomla 1.5 Last-Modified Header is non-customizable and returns current date, which is imho against seo-basics. Does any one know how (or component) to make Joomla 1.5 return Last-Modified header based on last modified article?Even in the latest Joomla 1.5 Last-Modified Hea