How do I enable google analytics ecommerce for Marketpress Multisite globally

Hi,
We are using marketpress on a multisite installation. It's a marketplace. We also have Google Analytics Version 2.1 | By Ivan Shaovchev, Andrey Shipilov, Hakan Evin (Incsub).
We'd like to track ecommerce data using google analytics from all our subsites.
If I didn't misunderstand previous posts I read about ecommerce tracking - they don't deal with multisite installation. Also, as I understand Google Analytics Version 2.1 should be compatible with integrated Marketpress ecommerce Google Analytics..
How do I enable ecommerce tracking networkwide? Is there a global variable that I can define? Or do I have to go to each store and enable it manually?