You can't.
actually you can, and both simply and free (not at/on the tivo itself (there
you can't), but both tivo desktop and via the built in xml server (Both
free) let you do it no problemo (there you can)
Actually you can, and both simply (well, simple once you've done it
once) and free, and on the TiVo itself!
There is an open source TiVo Desktop semi-equivalent called pyTivo
written in Python that can be run as a server on either Windows or
Linux machines and can serve video files to your TiVo just as the TiVo
Desktop does. You can associate a textual metadata file with each
video file (or one default.txt for the entire folder/directory) that
describes attributes of the video file including things like
seriesTitle, seriesId. When you use pyTiVo to transfer these shows to
the TiVo, the TiVo can use this metadata to create a folder on the
TiVo with all your shows in it, assuming the metadata info is
setup correctly.
I use a more complicated setup involving both pyTivo and kmttg (a java
GUI that does an excellent job at administering automatic file
transfers and transformations in both directions), so I'm not sure
what the minimum amount of work you need to do is to set up a folder
(mostly, just what fields need to be included in the metadata file).
But I have complete freedom to name both folders and shows on the
TiVo.
Best resource for both pyTivo and kmttg are the (long) threads on
each at tivocommunity.com in the home media subforum, or each has
their own development pages you can get to with google. Don't get
too dismayed by some of the technical talk - these are both actively
developing programs that pay a lot of attention to all the various
video formats out there - you can ignore most of that!
Chris