Hi guys,
yes a solution may be fliying to Salonica or Solun, as we Macedonians refer to Thessaloniki.
Another solution is to get the roads via Serbia (Szeged, Subotica, Novi Sad, Belgrad, Nis, Kumanovo, pass by Skopje and hit the border town of Gevgelija.
Here is a link for Popova Sapka (for your friend)
http://travel2macedonia.com.mk/travel-to-macedonia/destinations/popova-sapka
Some photos of Kozuf: have in mind they are 3 years old... I haven' been there and these are my cousin's photos. I've uploaded just for you.
You should also consider Mavrovo ski resort named Zare Lazarevski.
All the best!
http://www.panoramio.com/user/85114/tags/kozuf