where to write the post install script when custom the rh7.3 CD?

[163 <xintiaf 163 com>]

hi,all:

   I want to build a custom RH7.3 CD  for some modified packages.
   
we all know that the installer will execute some  post install operation after 
copy all the packages.

So my question is where and how to customize the post install script.

for example i have to patch some file at this, where we set them!


Any help will be appreciated!

Regards
Chris Fang