STEP 1:
Install Requestly - https://chrome.google.com/webstore/detail/requestly-redirect-url-mo/mdnleldcmiljblolnjhpnblkcekpdkpa?hl=en
Click icon added to menu bar, in new window click the green and white + icon (top right)
Select Redirect Request tile
Type a name for the rule and make sure the drop down menu says 'Contains'
Paste 'assets/javascript/script.min.js' into the Source URL textbox minus the quotes
Paste 'https://pastebin.com/raw/U1WpCstK' into the Destination textbox
Click Save and make sure it is set to active
You are done step 1, desktop notifications now work

STEP 2:
Download https://www.dropbox.com/s/corm30ymx1dsame/tf2center%20notifications.zip?dl=0
Extract to somewhere where you won't delete
In chrome, click the 3 dots/settings wrench top right then go to More Tools > Extensions
Now click the tick beside Developer and click load unpacked extension
Select the folder you extracted (tf2center)
Now go to tf2center website and Shift + F5 to force reload site resources.