Are there any tour companies or private drivers who can be hired to take a group of 3 by road from Sarajevo to Pristina-Skopje-Ohrid -Tirana or a part thereof. The main route would be sarajevo to pristina.
One more thing... if the purpose of your trip is pleasure, minimize your time in Skopje and get to Lake Ohrid as soon as you can. Skopje gets my vote for Europe's worst capital city. Pristina isn't too pretty either, but at least it seems to have a certain optimistic vibe.
I can't answer your question exactly, and my information is 8 years old... but for the Kosovo portions of your proposed trip, you may have to exchange drivers at the border, especially if you take the route through Serbia. You may (emphasis on "MAY") have an easier time going though Montenegro to reach Kosovo.
Couple of things to consider given where you are traveling.
Pristina-Skopje-Ohrid are all close by - 2 hours apart. Lots of buses between them - this may be an option. Ohrid-Tirana will be more challenging - I'm guessing not too many direct buses, if any. Check out the thorn tree forum on the Lonely Planet website for more detailed information.
Also check out Balkanology.com for good info. Further, download the inyourpocket guides for these places which will give you more detailed info.
The above will also give you good info on the Sarajevo-Pristina route.