NSIS allows you to insert data on to the back of their exe files and then allows you to be able to read that data back during installation:
http://nsis.sourceforge.net/ReadCustomerData
How do I append my exe file with text data in a linux server environment?
Edit (from comment):
I've got a pre-compiled .exe file, I merely want to append data to it to satisfy the criteria here: nsis.sourceforge.net/ReadCustomerData, does any one with NSIS experience know if I could do something like echo "mydata:hello,world" >> installer.exe?