Monte-Carlo simulations of lithium ordering are presented allowing to determine Li-Li interactions from reproduction of the Se-77 NMR lines and of the titration curve of the Li/TiSe2 system. It is shown that. one has to account for interaction up to the third neighbor for x > 0.5 content. This is related to the percolation threshold of the electronic screening of the ions. Diffraction patterns simulated from the ion distributions show occurrence of long range ordering for lithium content beyond 0.50.