Yes I did reboot. I ran your script as below.... after creating the appropriate directories.
[root@localhost ~]# mylivecd --nodir ^/root/temp,^/root/tmp,^/home,^/mnt,^/media,^/tmp,^/proc,^/dev,^/sys,^/var/lib/drakbackup,^/var/cache/apt/archives --ufs unionfs --root / --tmp /home/john/Desktop/temp/ --workdir /home/john/Desktop/workdir/ --lzma --md5sum /home/john/ISO/pclos2010-kjp.iso
Subroutine run_program::formatError redefined at /usr/lib/libDrakX/common.pm line 8
mylivecd, version 0.9.0, http://pclinuxos.com/
Copyright (C) 2010, Texstar <texstar at gmail.com>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
WARNING: The temporary directory '/home/john/Desktop/workdir/' will not be removed at exit, please do so manually
Creating initrd: [100.00% 00:00:06/00:00:06]
Setting filesystem parameters: [100.00% 00:01:21/00:01:21]
Creating compressed image: [100.00% 00:21:44/00:21:44]
Creating isolinux boot: [100.00% 00:00:00/00:00:00]
Creating final iso: [100.00% 00:00:00/00:00:00]
ls: cannot access /home/john/ISO/pclos2010-kjp.iso: No such file or directory
Embedding MD5 checksum:
[ ]Argument "" isn't numeric in division (/) at /usr/sbi[ 0.00% 00:00:00/00:00:00]Error - Unable to open file /home/john/ISO/pclos2010-kjp.iso
Illegal division by zero at /usr/sbin/mylivecd line 288.
Ain't life obstinate!