Upload wp-cufon folder to the /wp-content/plugins/ directory
Activate the plugin through the 'Plugins' menu in WordPress
Convert or get some compatible .font.js fontfiles
Create a directory with the name fonts in /wp-content/plugins/
Upload your font-files to /wp-content/plugins/fonts/
Go to the Settings Page and enter your replacement codes with the "font-family" names of your fonts
--> Example: Cufon.replace('h1', { fontFamily: 'Vegur' });
--> you can test the free Vegur fontfile from /wp-cufon/example/ - load the file into your external font directory.