Thanks for your answer. Unfortunately, after reading the links you provided, I still haven't found the answer for my problem. It looks, after many searches and reading on the web, that LiLo can't hide or unhide logical partitions.
Only primary partitions can be hidden/unhidden with LiLo.
For now I use XOSL ( http://www.ranish.com/part/
) to fulfill my wishes.
Thanks again for the provided links. It was fun and educational reading them.