IntelliJ IDEA 12 and Homebrew Android SDK

1. Press CmdShift. in the file chooser dialog to show the hidden files.

2. Navigate to /usr/local/Cellar/android-sdk/r21.1 directory.

If the keyboard shortcut doesn't work (e.g. another plugin is using that shortcut), another alternative is to add /usr to your finder favorites and navigate from there.

I did this before i found CrazyCoder's answer, by soft linking the android-sdk:

ln -s /usr/local/Cellar/android-sdk/r21.1 /opt/android-sdk

I recommend CrazyCoder's method.