and ;-)
If you installed Eclipse ADT
and added eGit and the Google Plugin for Eclipse
and other things I carefully documented and now can not find
and set up your App Inventor source with git as documented
you can run ant from Eclipse
right click on build.xml (the top one or the one in the buildserver folder for example)
Run As
1: Ant Build
2: Ant Build...
Clicking the first choice (Alt Shift X, Q) runs ant
and the second lets you run some of the other ant targets, useful if you want to get the buldserver tar for example.
Select build.xml and press F11 also runs ant.
Nice
Gary