We will that tutorial updated shortly, in the mean time the steps for updating are:
1) Copy all of the php files and folders at the root of the PowerStore Files folder to the live power store site.
if you have edited your theme and want to keep your changes... make sure to save a backup of the theme webassist/folder
2) copy the install/webassist folder over the /webassist folder in the live site. if you saved a backup of the theme folder, you can replace the webassist/theme folder that is created in this step with the backup.
3) run the .sql script in the install/scripts folder that corresponds to your update path. If you are upgrading from 4.01, use the v4.0.1_4.5_update.sql script.