If you or anyone else is looking to do this, it isn't that difficult with most fans. Generally all LED fans are about the same animal. So lets look at one with LEDs:
Typical LED fan. Notice how the power wires exit the fan body and run up a leg to exit the fan. Now we will gently lift the wires in the next image:
Note the red and black wires under the power wires. These wires are the power for the LEDs that are on a sort of foil strip (also plastic) that wrap around the fan. Actually that strip is a flexible circuit board in a sense. Let's look closer at things:
Note how the red and black lines are soldered to the foil. The LEDs are connected to that foil strip. Let's get closer:
Now if you are good with fine soldering you would remove the red wire and place a simple single pole single throw switch in series with the red wire. However if you suck at soldering then just cut the red wire and place your switch lines in series with the red wire. Place the switch wherever you choose. Maybe in the plastic cover of an empty drive bay?
Wish I would have seen this thread sooner but was on vacation.