My Digispark board won't show up in Ports tab in Arduino IDE (OSX)
I don't think it is supposed to. The Digispark briefly connects in "bootloader" mode, which you spotted as "Vendor-Specific Device:".

Then after 5 seconds it runs the loaded sketch. If your sketch doesn't create a USB port (eg. a keyboard) then it will disappear from the USB list.

See:

http://digistump.com/wiki/digispark/tutorials/connecting

You don't select the port, the core files automatically find the Digispark and program it. You have to plug in the Digispark when instructed, to activate the bootloader.