If you want to start development of ownCloud android client you have two way to do so
(a) building with console
(b) building with eclipse

1. Use setup_env.sh
2a. ant clean;ant debug
2b. Open Eclipse and import actionbarsherlock/library project to your workspace

after those space you should be good to go.

HAVE FUN!

NOTE: You must have 'tools' and 'platforms-tools' in your path in order to run setup_env.sh