need help installing switch-science audio jack breakout board

Greetings,

I'm trying to set up my arduino to read input from iphone headphones. I want to be able to get input from the mic and the buttons. So I picked up the audio jack breakout board from switch-science; 4極オーディオジャックと基板のセット--販売終了 - スイッチサイエンス

The site is in Japanese, and there's not much documentation. It doesn't look like anything other merchants carry.

Yes, it's a 4 pin jack for iphone headsets, as you can see from the picture on the switch-science site.

I understand how to set up for audio out, and generate a tone. The difficulty is designing the circuit for input.
What do I need in order to read from all 3 buttons that all signal through the mic pin? I read that the iphone reads the buttons through a change in resistance on the mic line. I have no idea how to do that. Even pointing me to some useful documentation or tutorials on the topic wold be helpful.

Thanks,
Brian