rpm behavior at install

[rpm at squoggle.com]

I'm working on an rpm that creates a Linux repository on a server.   
I'm calling it repo-1.0.0-1.i386.rpm.  Basically I want to take all  
the rpms from the distro DVD and install them in the web root, run  
createrepo on them and a few other minor things and be happy.

Normally when building an rpm I would take all the files I need and  
package them into the rpm and let rpm install them.  Doing that with  
this rpm makes the rpm huge between 2 & 3 Gig although it does seem to  
work.  This rpm also needs to be added to a custom distribution DVD so  
adding this rpm to the custom DVD iso basically doubles it in size.

It seems more logical that since I already have the DVD media handy to  
make an rpm with a post script that takes the rpms off the DVD and  
puts them in the right spot, does the few minor tweaks and I'm good to  
go.  This makes for a very nice very small rpm.  It works fine when  
testing the rpm on a test bed.  The script behaves predictably and  
mounts the DVD, grabs the files and puts them in the correct  
locations.  It's another story entirely when the rpm is included in  
the system kickstart and installed when the server is first created.   
None of the post script actually functions.

In fact any minor command that I run as part of a post script in an  
rpm that is installed when the system is being built seems to fail.   
This after hours of making sure that paths to commands are correct for  
what they would be during installation.  The install.log shows that  
either the command is not found or the file being acted upon is not  
found.

There seems to be a huge difference in behavior of rpms (at least the  
post script section) installed as stand alone and when they are  
installed at system installation.

I've read Maximum RPM and cannot find anything.  I've read the fedora  
project sections on rpm and am still at a loss.

Some guidance would be appreciated.