I did send an email and this is the response I got.
Hello Steve,
You can add a 10 watt 4 ohm resistor to this fan to slow the fan speeds down. This will give you about ½ of each speed. You can purchase these resistors at your local electronics store. I am sending a diagram for the installation of these switches. Please let me know if I can help again!
Thank You,
Jeff Atwell
Jeff also attached a PDF drawing. I am having trouble putting it in this email. When I figure out that part I will post it.