To connect to a router/other console device you'll need to get a usb-serial adapter. Adapters aren't very expensive and look like this!
Connecting to the Console Port with Mac OS X is actually easy without any software and just using the OS X Terminal!
Connect the OS X USB port to the router.
Use the Finder to go to Applications > Utilities > Terminal.
Enter the following commands to find the OS X USB port number:
admin$ cd /dev/
admin:dev admin$ ls -ltr /dev/*usb*
crw-rw-rw- 1 root wheel 19, 10 14 Nov 14:18 /dev/tty.usbserial-AI038BL8
crw-rw-rw- 1 root wheel 19, 11 14 Nov 14:18 /dev/cu.usbserial-AI038BL8
You need to look for the tty device. Now you can connect to the USB port with the following command followed by the router USB port speed:
admin:dev admin$ screen /dev/tty.usbserial-AI038BL8
To Disconnect the OS X USB Console from the Terminal Window just enter the commands bellow on your keyboard.
Enter Ctrl+A followed by Ctrl+\