@yamaryam : yes I check this plugin, that's the one also the author is refering. It's not usefull at all, maybe before when they release it. History it's that this plugin is an extract of the code they have in woocommerce 1.0 because they didn't keep it in woocommerce 2.0 (maybe for others to do premium plugins ...) But it's not working at all, other users complain on forum and no answers.
@braekling : yes woocommerce has an API (http://docs.woothemes.com/wc-apidocs/)
Yes their plugin has not been updated. There is hook avalaible to know if we are one a product page or thank you page, so I was thinking maybe from this it's possible to add these Piwik methods :
addEcommerceItem(productSKU, productName, productCategory, price, quantity) for each product on order done
trackEcommerceOrder(orderId, grandTotal, subTotal, tax, shipping, discount) on order done
trackEcommerceCartUpdate() every time a user is adding, updating or deleting a product from the cart.
setEcommerceView( productSKU, productName, categoryName, price ) is used, just before the call to piwikTracker.trackPageView() on the product/category page.
But as I'm not very familar with web development (as soon it's more than adding some function in functions.php) I don't know if it's a lot of job or by where to start ...