Move Networks plugin

I have been trying to use the player from Move Networks that Fox uses for playing some of its shows on websites (e.g., http://myspace.com/24). Even when using Firefox Portable it installs the software and caches the files it needs in the logged in user's Application Data directory. (I am in a location with roaming profiles.) I would like to have the plug-in use a directory on my USB flash drive to cache the files because space in my user account on the network is severely limited. Is there a way to make this work? I don't know if anyone has experience with this situation.