It is not at all clear why you want the arduino.
It is not at all clear what buttons you want to detect.
It is not clear what the arduino has to feed to the ASWC as this appeares to be a compleate solution.
It is not clear why the thread has this title.
1. The arduinio will give me the function to have 1 button do 2 actions. quick press or hold press
2. Vol up, Vol down, trk up, trk down, Seek up, seek down, Phone pickup, phone hang up, Voice activate and Mode
3. The ASWC reads the Resistance there for I would need the arduino to create those Resistances and send them to the ASWC. The ASWC will only do one action per button.
I am not sure i can connect the arduino directly to the radio as i am not sure what the protocol is that the pioneer radio uses this is why the ASWC is in the picture