Dear Napoleão, we solved this type of problem in a paper of 2004 (J. Mol. Biol. (2004) 342, 275–287) with the using of EPMR which use a evolutionary search algorithm, I will send you the paper later. It was 36aa dimeric coiled-coil and we had a lot of molecular replacement problems with other tested molecular replacement programs.
http://www.epmr.info/UsersGuide.html Good luck.
