Unfortunately you can't get to close to a 'real' LCARS theme with out a bitch slapping from the Paramount Legal Dept.
A friend of mine did himself a StarTrek website (he is a huge nerdy type fan), he is a professional graphic & Multimedia designer (has been for ages, a real pro) so it was dead on. No stolen parts from Official sites, all his own work. This was back in the early Voyager days when the official Paramount site looked a real mess. A week after it went live he got a cease & desist (?SP) from Paramount. With a long list of copyright infringements listed on it.

Dam Paramount has more Copyrights on the Look and feel of a fantasy OS that Apple had/has on a real one.