I'm sure his simple Inno project is a simple text file, so you can easily edit the setupper script with ant, however, I would recommend creating a separate small include file using the script. You can store "variables" there, such as the version number + assembly, which you show at the beginning of the setup.
put this line in your setupper:
#include "settings.txt"
and make settings.txt have something like this
#define myver=xxx.xxx
#define tags
now you don’t need to touch the actual setup code from the build script.
below is a snippet from my build script to compile setupper. you need to execute the batch file from ant as follows:
<exec dir="." executable="cmd" os="Windows NT">
<arg line="/c build.bat"/>
</exec>
sample batch build.bat:
set isxpath="c:\program files\inno setup 5"
set isx=%isxpath%\iscc.exe
set iwz=myproj.iss
if not exist %isx% set errormsg=%isx% not found && goto errorhandler
%isx% "%iwz%" /O"%buildpath%" /F"MySetupper.exe" >>%logfile%
goto :eof