You should find
The Witcher savegames here:
~/Library/Application Support/com.cdprojektred.TheWitcher/GameDocuments/The Witcher/saves/
Choose the savegame file you want to import (the savegame has to be created during the
Ice Plains or
Order of the Flaming Rose Cloister portions of the
Epilogue) and copy it to
The Witcher 2 savegames data location:
~/Library/Application Support/com.vpltd.TheWitcher2/GameDocuments/Witcher 2/gamesaves/
Then you should be able to import your savegame.