Can I use Wi-Spy spectrum analyzers as wireless adapters on which to capture traffic?

If WinPCap can discover the adapters under Wireshark's [Capture] -> [Interfaces] or tshark's -D option, you should be able to use them. Cheers,

Unfortunately, MetaGeek's Web site appears to have been taken over by marketoons who want the Web site to talk about "solutions", rather than "products" - their "products" page doesn't list "what they make", it lists product bundles and prices, so it's hard to find where they describe the Wi-Spy hardware that they offer.

However, with enough digging, I found the Chanalyzer + Wi-Spy User Guide, which says:

Note: Wi-Spy is a spectrum analyzer. It is not capable of reading at the Wi-Fi packet layer. Therefore Wi-Spy will not appear in the Wi-Fi card drop-down list. Due to the way Mac OS X handles Wi-Fi, if you are running Chanalyzer in a VM, you will need an additional USB Wi-Fi adapter to collect network information.

so, no, you cannot use a Wi-Spy as a capture adapter, on any OS. It has a radio and an antenna, just as a Wi-Fi adapter does, but, instead of doing 802.11-style processing on the radio signals to turn them into 802.11 packets to hand to the host, it does spectrum analysis, showing the signal power at different frequencies throughout its frequency range.

At least the original hardware generation of the Wi-Spy was a Bluetooth adapter with a modified firmware. Thus the 1 MHz steps used for scanning the spectrum. And thus not 802.11 (bgn) capable.