upload video to canon s400 (ixus 400) - which codec?

Hi folks,

I own a Canon Powershot s400 (Digital IXUS 400 here in europe). Great
little gadget!

I would be interested in the possibility to play videos UPLOADED to the
camera (via a CF-card-reader) for the purpose of having an ultra-compact
digital video-player with me - connecting the camera to a TV (for
showing short videos in workshops, at school, etc.).

The video would have to be 320x240 pixels I imagine, and possibly have
to (?) be mono (thats what the camera is recording in), but what *codec*
do I have to recode the video in? To make it clear: my problem is not to
get the video on the CF but to recode it in a format that the camera is
able to play.

Is there anybody out there who has tried this? Please do not simply tell
me that it's not sensible to do this - if it isn't I still would
like to know if it is possible at all.

Thanks in advance for any help,
Niklas