The port is
Open setup and make sure top three boxes in upper left are checked.
Uncheck key clicks, it will drive you nuts.
Mouse click in the hotkey area and you can then hit any key you wish to use as a hotkey for your mic. I generally use the left control or alt button as it does'nt interfere and activate my mic if I'm typing something when ventrilo is active.
And remember this tip, you need to close the setup window to be able to use your mic. Not sure why that feature wont work while setup is open.