make installer to copy arbitrary files.

I am required to do some work on IBM Web Browser on OS/2  installer 
(Mozilla based browser). As we can not dynamically link to the runtime 
dll (innotek GCC), because of licencing issues. I need to change the 
installer code such that it copies the arbitrary files (in this case 
runtime dlls) to the appropriate path. I mean when the installer 
finished with installing xpi files it needs to look for the runtime dll 
and copy it to the location of mozilla.exe.
Can someone help me where should I look to do this 
change(mozilla\xpinstall\???).
Ganesh,
IBM.