Yes, it "can" be done, but it would take a lot of work on CC2 to make it happen.
Its actually quite a bad way to control fan temps too, for quite a few reasons...
CPU temps supplied by software like SpeedFan are quite unreliable, and can depend on the motherboard type.
An example where it would be a very bad idea to control speeds this way is with motherboards that read CPU temp by using a sensor pressed up to the back of the CPU.
Also, what happens if SpeedFan locks up?
There is no way for CC2 to know if SpeedFan is reporting a correct temperature.
An example... SpeedFan locks up while your CPU is at idle, you run a game, CC2 keeps the same low fan speed due to the low temp falsely reported by SpeedFan. You burn out a CPU. Its a worst case scenario i know, but it could happen.
Where as if CC2 is directly monitoring temps and controls the fan, if CC2 locks up, the fans will spin up 100% keeping everything safe.
Another reason is that the on-die temp sensors are inaccurate and fluctuate wildly from one second to the next.
The temp reported by an on-die sensor does not represent the temperature of the overall CPU, or the temperature of the heatsink.
The heatsink is what you cool with the fan, so its the object you should monitor and base the fans speeds on.
Also having your fan speed based on on-die temp would be very annoying to listen to, as the fan speed would vary a lot frequently.