You can create vehicle spawns the iron man method, run to a location, set up a tent, look up the coordinates in the database, then add new spawns by hand. I think what you're asking about is the mass import one after you've created a mission file with all your new spawns on it.
To use the PHP method to import a horde of them from a missions file you have to have something capable of executing PHP on your computer. The simplest way, which sounds scary, is to install XAMPP and host your own website. You copy the PHP and mission file to your "website", then browse to those files using your web browser. Your browser will execute the PHP and import the spawn locations.
I'm not sure what SS is? A hosting company? If you don't have direct access to your server, you could instead install Bliss on a local machine, import your spawn locations, then copy that data over instead of trying to execute the PHP to a remote location.
I can post pictures when I get home, but this should be all the steps needed. (Hopefully I'm not forgetting any...)
1. Install XAMPP, you might want to uncheck MYSQL if you already have it installed. I'm not sure if it might hurt your existing install or not.
2. Navigate to where you installed XAMPP, find the htdocs folder. This is where your website would live if you actually had one. Create a new folder inside "htdocs" called "importspawns", just something to help keep you organized.
3. Copy the PHP script and mission file to your new "importspawns" folder.
4. Start the Apache server using the XAMPP control panel.
5. Navigate to your fake website using a web browser by typing in "localhost/importspawns/" in the URL field. You should see everything in that folder you created. Click on the script and it should run successfully, reading all the mission file coordinates into your database. If it doesn't run with a click, you can try typing it out in the url box instead. "localhost/importspawns/CreateVehicle.php" (name of your PHP file may vary... mines a bit customized)