I don’t want to say it’s the easiest thing to accomplish but if you have any soldering experience it’s pretty straight forward. The hardest part for me was testing to see which pins I needed to solder to and which state (power/ground) I needed to have them change from/to to simulate a button press. I have done some small soldering jobs before (changing capacitors on tv boards and making an LED arduino clock) so I didn’t have too much difficulty with the solder. When all was said and done I think I spent $50 on the project. ($32 for the Thing Shield with the coupon code, $12 for a sainsmart arduino uno board, $6 for a project enclosure board from RadioShack believe it or not there is still one open near me).
Before hijacking the remote I also tried creating an rf receiver/transmitter with the arduino board. I used an idea I found on a site called arduinobasics. I was able to receive the rf signal via the arduino but when it was time to repeat it to the fan I had no luck. Part of me thinks my problem was the fact that the fan remote had a 305mhz transmitter and I was only able to find a 315 online. I was somewhat limited because I already had the fan installed. If you are starting from scratch I bet you could find a fan canopy module that is known to operate on 315 or 433mhz. I am not as familiar with the aeon micro switch, I know because I am using a button press remote with a toggle switch that I can not see the state of the fan or lights from the app, I can just initiate them to turn on or off.
If you did decide to install the 40015 Honeywell fan canopy module I could definitely give you a schematic of what I did.
I can also show you some ideas on how to explain to your girlfriend why you are spending $50 to take apart a remote control so that you can make a different remote control.