You'll need a video capture box. The jack you describe is a composite video connection, so you're looking for either a PCMCIA or USB capture card with a composite input.
There's not much out there in the way of support for USB video devices, and I believe PCMCIA support is even worse, unfortunately.
Apparently, the 'Belkin USB Videobus II' *might* work - have a look at this:
http://lists.slug.org.au/archives/sl.../msg00042.html
It would appear that there is a driver for this device, but it may not be completely straightforward to set up (that page is 2 years old, though, so I imagine things have got better).
Also, there's some support for the 'WinTV PVR USB' (not the plain WinTV USB).
Have a look here:
http://pvrusb.sourceforge.net/
Again, this may or may not work.
If you had a desktop machine, this would be easy.....
Dave