Why don't you just compile kismet, set it up and see if it works. Apparently recent kernels support rfmon (=monitor) mode. Orinoco is a peculiarity in linux because unlike most other wireless modules (hostap, madwifi, prism54, wlan-ng....), it doesn't implement monitor mode out of the box (at least until quite recently, I don't use it so I might be wrong).
Anyway from the kismet README:
Code:
FreeBSD
Known supported cards: Atheros, Prism2, WSP100, Drone, wtapfile, pcapfile
FreeBSD-current adds a common Radiotap packet header format. Thanks
to Sam Leffler, Kismet supports the radiotap headers and should work with
current FreeBSD systems.
FreeBSD users should configure with the --enable-syspcap to get mutlidlt
support.
I already hear the bin trap opening.