Download and run the cygwin setup.exe (direct download link).
The setup process is straightforward. Choose the directories you’d like to use and install the default current packages. On the page after the package choices make sure to keep the option to download the required packages checked. That’s all that needs to be done to setup cygwin.
Prepare Tree Style Tab
Download the latest Tree Style Tab files here by clicking on the button labeled “ZIP”.
Extract the zip file into a folder named “treestyletab” in a location of your choosing. For this example I’ll put the folder in “C:\treestyletab\”
Run the cygwin terminal and enter the following commands one at a time:
Now there should be a file entitled “treestyletab.xpi” in the root directory of the folder you created. For example the location of my newly created file is at “C:\treestyletab\treestyletab.xpi”. Drag this file into Firefox, install the add-on, and restart Firefox.