Another success story:
I had a USB device that has a SiliconLabs cp210x UART in it and I wanted to get the /dev/ttyUSB* serial device going. I had the default 2.6.22.18 kernel. After many false starts trying "modprobe" I found this note here and got
http://sheeva.with-linux.com/sheeva/README-2.6.22.19. Upon rebooting, the device "/dev/ttyUSB0" showed up and I could use it.
Note: I had to "apt-get install wget" before using the upgrade/flash script.
-T