We can't; assuming it'd even work with our current load-balancing server setup, we're also missing the Django setup it also requires.
It'd be a full server modification since it doesn't have an option to set it up for a single users account - that's not a good idea on a server with a few thousand accounts that have load balancing set up without some -major- testing first, and from reading up on it from here it sounds like it's meant to be installed if you're pretty much the only user on the server.
Edit: Just to clarify the part about it being meant if you're the only user on the server, the minimum recommended ram for the script is 512mb. Most webservers can get setup on a VPS with 256mb or less, but this one wants 512 - that would indicate a pretty resource intensive setup, let alone that the 512mb doesn't include the space for the rest of the prerequisites like Django, the Translate Toolkit, and "South" - the rest of the prerequisites I'm pretty sure are installed, but it requires these other 3 things to be installed before we can even mess with Pootle. Not the best of ideas when there's resource concerns because of the number of accounts on the server.