First I used xv to crop the TaoSecurity logo, set the image size at 16x16, and save the image (taosecurity.png) in png format.
Next I installed Netpbm using the graphics/netpbm FreeBSD port. Once installed I executed the following command to convert my png file to the desired favicon.ico:
orr:/home/richard$ pngtopnm taosecurity.png | ppmtowinicon -output favicon.ico
When done I had the icon I needed:
orr:/home/richard$ file favicon.ico
favicon.ico: ms-windows icon resource - 1 icon
I copied the favicon.ico file to my Web root, and then added the following to the HEAD section of my index.html file:
<LINK REL="SHORTCUT ICON" HREF="favicon.ico">
I had to clear my Web browser cache to see the new icon. Incidentally, I don't see the icon in Internet Explorer. Using Firefox, I do see it.