First off, I'd like to say "Thank you!" to David for the wonderful code base.  :-)  This morning I started reading through the code for the livecd-creator component and I think it might be beneficial to insert a check into the main routine to check the users system for essential tools (toolsets) before continuing with the build process.  I suggest this be done because my first build failed because I did not have squashfs-tools installed and hence, did not have the mksquashfs program to complete the build. 

   Maybe it can be something as easy as:

   if ( open('/sbin/mksquashfs', 'r') ):
   print "Squash-tools installed, continuing with build..."
else:
   print "Please install the 'squash-tools' rpm using yum then try again."
   quit
 
This idea could be expanded to test for all necessary tools needed to build the iso and should be performed "up-front" before they can proceed.  If a user is missing one (or more) then we can tell them which rpm to install using yum to fix the problem.  If they are missing none, we can move onto the build routine.  This way, installation support questions might be minimized on the mailing list.  Just a thought.  Let me know if this is something that should be pursued and I'll submit a patch.  Thanks.

-Adam