Need PHP code written for my Magento module

I have a Magento module that generates a Google Product Feed for me using an XML template: [login to view URL] Right the template only pulls the default {size} attribute in Magento. The problem is that I have 4 different size attributes and it depends on the product type such as shirts, shoes, etc (each one uses a different attribute set). I need some PHP code to add into the module's XML template that can see which attribute set is being used and pull the correct size attribute (the XML template allows PHP). Something like this: