I have downloaded the plugin and had a look, to add the "Do not follow links for this page (nofollow)" via seo press you need to add a custom field:
name: "_seopress_robots_follow"
value: "yes"
I have attached a screenshot showing these using the custom fields section.
James
This doc page should help you: https://www.importwp.com/documentation/importing-wordpress-custom-fields/
James