I'm not sure I understand your question.
Here, `X-PRIMARY-PHONE` stands for the property name that we're looking for, to be replace by the one below (`PHONE type:HOME`).
If you want to convert other properties, just add an `<import_entry>` tag with the `<vcard_entry>` tag for the result.
What do you mean by `PREF` ? is it a VCard property ?