@prairietech, are you trying to install this in Windows 8?
Sorry...forgot to say XP Pro SP3.
Went to Administrative Tools / Local Policies / Security Options and changed Devices: unsigned driver installation behavior from silently succeed to warn but allow installation.
Now after doing a driver update and pointing toward the driver folder, instead of getting the unsigned digital signature error, I got another box warning me of the error. This box allowed me to check continue anyway and the driver installation was completed.