Something like take thsi paragraph:
Since any attempt to block someone from reading public entries could be circumvented, LiveJournal does not offer such an option. If someone can find your journal, the only way to stop them from reading your posts is to make the entries non-public.
You can turn all of your entries into non-public posts (http://www.livejournal.com/support/faqbrowse.bml?faqid=120).
... Which adds in changing entry security and minsecurity, which should cover everything needed to answer the question.
