Previously some there was some problem for remastering Ubuntu 9.10 (Karmic koala). Karmic Koala is using Grub 2, remastersys is designed for grub 1. Now Remastersys is redesigned for ubuntu 9.10 with grub 2 and it is working. you need Remastersys version 2.0.13-1 or higher.
All other options are just like previous versions. see here
how to install latest version remastersys in ubuntu 9.10
add the following repository to your apt source by editing /etc/apt/sources.list or
add repository using System-->Administration-->Synaptic package Manager --> Settings -->Repositories-->Third-party-software-->Add
deb http://www.geekconnection.org/remastersys/repository karmic/
$sudo apt-get update
$sudo apt-get install remastersys (or use synaptic)
I have created a Ubuntu 9.10 Live CD with Multimedia Support, java, LAMP server, GCC and lot more.......