The best thing I can think of is set up SSH on your n800 and SCP into it. If on Windows, use WinSCP. This won't mount it as a drive, actually, but this will allow you to transfer files to and from it.

[edit]D'oh! I should think about these things first... This would not work. When you connect via USB, it un-mounts the memory card(s), and gives USB access to them. So, even if you setup something like this, you would not be able to access the memory card(s) that the dvd player sees.