Need help with Office XP distribution

I am trying to set up an administrative installation point to
deploy Office XP and have run into a problem. I created the
install using the Setup.exe -a method to extract the setup
files to the server so that I could make my custom
installation files. The problem is that my company
purchased both Pro and Standard versions of Office XP and
I have two sets of serial numbers for each version. What I
would like to do is set up a Pro and a Standard install point
but have the serial number in the .ini or .msi file so that i
don't have to make four separate install points to roll out
Office XP. When I run Setup.exe -a it prompts me for a
serial number and I can go any further without entering
one. Any client installation from that point has the serial
number I entered at the time of the install points creation.
Is there a way to set up the install point without a serial
number so that I can put that information into a
configuration file? Can the serial number from an install
point be overridden and the time of client install? I really
don't want the confusion and wasted space that comes
from having 4 installation points!

Craig