First are you talking about storing the music on your Android device or on the Google servers?
If you are planning on streaming music to your device from the Google Music Play servers then you can't store your music in a lossless format see this page about formats on Google Play Music, and notice this line:
FLAC, ogg, and aac files are transcoded to 320kbps mp3
However, if you want to store the music locally on your device then your question makes more sense.
There are a few ways to put ALAC music on your Android device in FLAC
Keep your library in ALAC and convert songs to FLAC as you want them. Then move the new FLAC files to your device. A program like Max should be able to handle the conversion for you.
Convert all of your ALAC files to FLAC in place and then use fluke to enable FLAC playback support in itunes.
What option you select depends on how much you like to keep your OS free of plugins like fluke and how ofter you are moving music to and from your device.