You can get it from the latest version of O2 (GitHub) or from this DropBox download: Tool - Cat.Net outside VisualStudio v1.3.exe
You can see below how it is supposed to work, but I'm having an issue at the moment which would be great if somebody could help in.
Basically the problem is that there is an dependency on EnvDTE which only happens on certain installs.
I have been able to run this tool on VMs with and without VisualStudio installed, so there must be something else that installs EnvDTE on a box (like the one I was using at EC2).
The problem is that one of my users is not able to run the O2 scripts based on the O2's Cat.NET APIs, and we need to figure out what needs to be added (or removed) in order to make this work.
How it it supposed to work:
1) download Tool - Cat.Net outside VisualStudio v1.3.exe and put it somewhere (like an empty folder)
2) open that file and see a GUI that should look like this (if all goes well and the test scan was successfully executed):
Note: All Cat.NET files are included in the original Tool - Cat.Net outside VisualStudio v1.3.exe and unzip on first load. Take a look inside the _temp folder created