Modify this file using TextEdit:
C:\Bridge Base Online\bbover.ini
In the [SYSTEM] section, put:
[SYSTEM]
LINUX_WINE=Y
BROWSER_TYPE=E (Some say A works here, too.)
You also need to put "symbol.ttf" font into your Mac's Fonts folder, which is inside your System folder. This font is used to display the card numbers/letters.
The only thing I am having trouble with is responding to direct chats from people not in my game. No big deal.
Have fun!