Hell I wish I had never written this node. Step by step here is a how to:
Get a copy of a disassembler. A nice basic GUI one with a 30 day free trial is PE explorer which is available here
Disassmble the exe with PE explorer and explore it. You will see the key string in the first few hundred bytes (plain text), one char per line but this is not an assembler tute.... Using PE is rather like using windows explorer. Find the script component and save it to a file. You only save the script part you want to decrypt. This is one 'chunk' within the exe.
Run the sample code located on this node on the saved file to decrypt the script. As noted the encryption is an XOR against a simple string.
Disassembling stuff may breech some laws somewhere so this is provided for information purposes only.....