Unfortunately Skype for Mac does not have a contact importer, therefore it is not possible to import then from Facebook.
However, we released a Skype for Mac 5.4 beta version yesterday, which has the option to connect to Facebook, see your Facebook friends news feeds and talk with them from Skype.
You can download Skype from here: http://www.skype.com/intl/en/get-skype/on-your-com
Please make sure that your contact list has at least 3 contacts, or that you have made a call to one of your contacts.
After that the Facebook connection should become available. Exact instructions on how to connect to Facebook on Skype for Mac 5.4 beta can be found here: https://support.skype.com/en/faq/FA11065