Make sure that the freshly compiled gij (and the java symlink) is in your path and that LD_LIBRARY_PATH points to the newly installed lib directory. Go inside the eclipse directory and you should be able to just type ./eclipse and it will show you an installation popup.
This will take several minutes. If anything goes wrong start it with ./eclipse -debug and/or look in the newly created file workspace/.metainfo/.log.
After several minutes you will see the following welcome screen.
One of the first things you probably want to do is set the correct key bindings :).
Not everything will work as expected and sometimes you are greeted with the following dialog.
Which is often because the garbage collector is disabled. My machine quickly gives up after eclipse has eaten more then 600MB.
Update: There used to be a screenshot here of the terminal window showing lots of Out Of Memory messages. But with all the new patches this does not happen anymore.