Is there any tool to replace the files packed in the NullSoft Install System package?
 

I have tried 7-zip which can view the files in the NullSoft installation package,
but I could not replace these files with 7-zip.
So, is there any tools to do the job?
Thank you.

a few months ago i needed the same. I found a programme which extracts and builds package using existent nsis scripts. unfortunately i dont remember name of the programme. it was like nsis decompiler or like that. its only registered version can built new package.

7z in past can decompile nullsoft installation scripts. Last version of 7z that can decompile script is 15.05 (2015-06-15). Look for the [NSIS].nsi file inside archive. There exists also other decompilers. You can try rebuild script and pack it again with NSIS.

http://nsis.sourceforge.net/Can_I_decompile_an_existing_installer

hope this helps

Yes, I have used 7z to extract the script file.
The curious things is that the script file seems not the original one,
for examples, the filenames following the File command all lost their
paths, I have to add their paths manually so that the Nsis can recompile
the script; Another weird thing is that the script file does not contain the
Uninstall section, I have to copy the commands associated with uninstalling
from the script hidden in uninstall.exe.