Using Windows RT to manage a Windows Phone (7.x)

I have both a Surface and a rickety old Dell with Windows 8, and a Nokia Lumia 800

My carrier has just informed me that WP7.8 will be coming to my phone in the coming days, the only problem is, in the coming days the only device I will have on me will be the Surface

As far as I can tell, there is no way to replicate the functions of Zune on Windows RT, so aside from my Steam library, the only thing preventing me from doing all my personal computing on Windows RT is the fact that I need to go back to a full Windows machine every time my phone needs an update

Unless anyone knows of, and can point me to a way to update my phone via the Surface, this is a missed opportunity to get an edge on RT's competitors.