(1) Create a repository in BitBucket.
(2) Go into shell, and clone from BitBucket which is empty.
e.g. If I have created non-mercurial project in local eclipse called "hello_world":
$ mv hello_world hello_world.bak $ cp -r hello_world.bak hello_world $ hg clone https://bitbucket.org/BBUSER/hello_world http authorization required realm: Bitbucket.org HTTP user: BBUSER password: destination directory: hello_world no changes found updating to branch default 0 files updated, 0 files merged, 0 files removed, 0 files unresolved
(3) Then move or copy those files from the local project directory into the BitBucket cloned directory.
$ cd hello_world $ hg add adding .... [ommit] $ hg ci -u BBUSER $ hg push
(4) Remove hello_world project from eclipse (make sure to have a backup) and from disk.
(5) In eclipse's menu -> New -> Other -> Mercurial -> Clone Existing Mercurial Repository, then click <next> button.
(6) In next dialog, enter URL to the BitBucket repository (get this when the repository was created, or go to the site and find out), username/password.
(7) Click next, next, finish.
...there should be an easier way...