there are some file that u add in system (im not sure, this is what i remember).
http://www.lineage2media.com/DROP%20PATCH%20SPOIL%20HELLBOUND%20LIneage%202.html hellbound
http://www.lineage2media.com/Downloads/Lineage2droppatch.rar interlude
credits: l2media, so dont ask me if they may not work or give any errors.
and some servers have this implemented as a custom.