Building Android with Ant

To create a build using an ant build.xml script, you'll need a local.properties file. This point to your sdk installation directory.

You can create this with the android tool like so:
    android update project --path .

Execute from your project's directory. The full stop is important!

Remember you'll need to add keystore and proguard if you want to sign/obfustcate etc:
    key.store=/path_to_keystore/keystore
    key.alias=key_store_alias
    proguard.dir=/path_to_proguard/lib (seems to use lib dir rather than bin)

(See here for more about signing and obfuscation)