Regardless of what I do, Windows 8 tells me that there are no wireless network adapters.
How can I enable Wifi in Windows 8 in VMWare Fusion on Mac so I can scan for Wifi adapters and connect/disconnect at will?
VMware only presents a wired Ethernet Network Adapter to the Guest OS regardless of the Host's Network Adapter type. If you need/want a WiFi Network Adapter in the Guest then you'll need to supply your own, like a USB WiFi Network Adapter. The Host's built-in WiFi Network Adapter cannot/will not be seen in the Guest.
Have a look at Ethernet Card in: 
Virtual Hardware Specifications