Hi Michael,
Still can't get this to work.This is the error I'm getting now:
Extracting file: C:\Users\Lawrence\Downloads\CustomUI.1.03.win.mac.zip
Extracting to "C:\Program Files (x86)\MoI 3.0 beta Jun-27-2014\"
Use Path: yes Overlay Files: no
Unable to process "objects\".
Severe Error: Not permitted or able to create an output directory.

Any ideas.I'm not really knowledgeable with scripting so I could be making a very basic mistake with my installation but could this be to do with privileges?