Thanks, I got it!
(For those who want to know, here is the code)
@Override
public IBlockState getStateForPlacement(World world, BlockPos pos, EnumFacing facing, float hitX, float hitY,
float hitZ, int meta, EntityLivingBase placer, EnumHand hand) {
return super.getStateForPlacement(world, pos, facing, hitX, hitY, hitZ, meta, placer, hand).withProperty(FACING, placer.getHorizontalFacing());
}