This site might help - it doesn't mention having to go in as a group, though but has some info regarding getting the all- important visa: http://www.triotours.com/faq/ly/visa-how.htm

Have you tried posting your question on Lonely Planet's Thorntree, Africa branch (do a search on Libya)? There is some info on this particular thread: http://tinyurl.com/3ookb

Nadine, Vancouver