The documentation of PDE has a chapter for this topic. Basically it's simply. Copy the template scripts what you want from templates/headless-build folder under org.eclipse.pde.build plug-in to your build configuration directory that is the folder has build.properties file.

However I found the variables listed in …

You must see the qualifier string property when exporting your features and plug-ins by Eclipse pde. But specified qualifier string won't appear after you export the features successfully.

If you want to use the qualifier string, you must define your feature and plug-in version like below:
1.0.0.qualifier, …