To build, run charm build -o $HOME/path/to/built/charms/dir/

At this point I usually copy in the .bzr folder from https://code.launchpad.net/~oil-ci/oil-ci/charm-weebl-BUILT to $HOME/path/to/built/charms/dir/, bzr add . and commit the changes and push back to lp:~oil-ci/oil-ci/charm-weebl-BUILT, but there's may be a better way of doing this.