It's actually quite hard for me to advise on this, as I don't have a Windows phone to test with, and I don't have a computer running Windows 8 so I can't even run the necessary windows phone emulator...
But based on the other instant notifiers I would assume the setup would go something like this:
Setup an account on the Pushalot website
Download the appropriate version of the App for your windows phone from Pushalot
Login to the app on your phone with the login details you setup on the Pushalot website
Obtain an API token from the Pushalot website.
Copy/paste your authorisation token from the Pushalot website into the SignUpSale site - User details page, Monitors/Notifications tab (and click the "Update details" button to save
If this doesn't work for you, please get in touch and I'll try to help out...