Smooth move Garmin
Oops, Basecamp Win and Mac are (way) different. "Good" go Garmin. I'm Mac illiterate so I can't be of any assistance. There is a Basecamp Mac thread, maybe post there.
If your route is a .gpx file you could post it in one of the GPS tracks -------, sub forums. Then I could see if I'm able to make it into a track and repost it for you. Might work.
Not all who wonder are confused