Not much of a build script, really. I used to (and, still do, for a limited purposes) use ant script to copy GAE jar files to war dir. (Now, Eclipse plugin seems to do that for me.) In any case, the relevant part is as follows (which used to have hard-coded SDK dir). I changed it last night to use "environment" var, GAESDK_HOME.

    ...
    <property environment="myenv" />
    <property name="gae.sdk.dir" value="${myenv.GAESDK_HOME}"/>
    ...
    <target name="copyGAEJars">
        <copy todir="${warLibDir}" overwrite="true" flatten="true">
		    <fileset dir ="${gae.sdk.dir}/lib/user">
			    <include name="**/*.jar" />
			</fileset>
		</copy>
    </target>
    ....