The author of the front end (sid6581) is the really the expert on this, but
afaik the source has to be compiled using ADS to produce the firmware.
Then the RK27dll.dll is created from the firmware using vc++.
So each time you modify the source you need to compile both the firmware using ADS and a new RK27dll.dll using vc++ to test it out using the simulator front end RockChipEmu.exe.