In OSX I can just hold down the option key and press the left cursor key until I get to the word I need to edit (or in Vi I can just hit b, but I haven't been able to figure out how to do this in Terminal yet...
To set the key binding: You first have to find out what key codes the Ctrl+Left key sequence creates. Just use the command
cat to switch off any interference with existing key bindings, and then type the key sequence. In my system (Linux), this looks like that:
$ cat ^[[1;5D
Press Ctrl+d to exit cat. Now you have found out that Ctrl-Left issues 6 key codes:
- Escape (^[)
Now you can issue the bind command:
bind '"\e[1;5D": backward-word'