Your best bet is SliTaz. It's 30MB and once you're done with installing and removing all the apps, you can package it up as a LiveCD! Best thing ever!
Click Here to Get SliTaz
SliTaz comes with Tazlito by default, try it, you'll love the ease of access! :)
Tazlito is a small utility to extract a LiveCD, rebuild the ISO image and regenerate the root filesystem of the LiveCD. Tazlito can also generate a distribution from a list of packages previously downloaded. To run, Tazlito uses the configuration file /etc/tazlito/tazlito.conf or an easily generated tazlito.conf found in the current directory. It specifies the name of the ISO, volume, maintainer and the paths of the packages to distribute and the generated ISO. Tazlito can also set up a directory containing additional files which will be copied to the LiveCD when generating the distribution.
Tazlito is distributed under the free GNU licence GPL V3, installed by default on SliTaz and installed/sucessfully tested on Debian GNU/Linux. You will find additional information about creating a LiveCD in the Handbook.