The author included this link to a download to use this item as a mod: https://dl.dropbox.com/u/35490615/Big%20Sister/Sisters%20Sting%20Mod.zip

Upon downloading, extract the .zip folder and click the Sisters Sting Mod folder that comes out. It contains three folders: Amputator, Ubersaw and Vitasaw. Select which of the weapons you would like to replace with this workshop item. Then click the 'tf' folder inside of whichever you chose.

Now open a seperate window and navigate to C:\Program Files\Steam\steamapps\[your_user_name]\team fortress 2\tf. Some people have their Steam folder in Program Files 32 or 64. [your_user_name] just means that there is a folder that has your username, and that is the one you click. In my example, it would be C:\Program Files\Steam\steamapps\pkpenguin\team fortress 2\tf.

Now drag & copy the 'materials' and 'models' folders from the Sisters Sting Mod into the 'tf' folder. A window should pop up asking if you want to merge the folders, check the "Yes for All" box and click "Yes." Upon booting up tf2, your mod should be installed.

If you do not feel comfterable doing this, perhaps if it is your first time installing a mod, Copy your Materials and Models folders from your Team Fortress 2 folder onto your desktop. If something goes wrong, go back to your Materials and Models folders and delete them, and replace them with the copies on your desktop. This process is completely optional and is used as a safety net if you feel you may accidentally break your TF2.

I have not yet tested this mod, I will try update this guide to tell if it works. I, personally, am replacing the Ubersaw and am confident that it will work.

If you noticed something wrong with my guide, please note it. If you have a question or problem, post it.