Here's how I'm building crosswords for Android.

First, my working directory is XWords within this (android/)
directory.

Build the jni library (the cross-platform code):
# ../scripts/ndkbuild.sh 

Then build the app for the emulator (first time)
# ant install

subsequent times
# ant reinstall

Build for a device (requires you've set up your keys.  I did this too
long ago to remember how but the info's easy to find):
# ant release