If You want to login to server, You'll need Lineage II Interlude cliend and this patch:

L2Java.exe (24MB) []

Mirror 2 [local]

After running it shortcut will apear on Your desktop. Thats it.

Good luck!

P.S If you have problems in game (critical errors, dc, lag) need to update Lineage2 Interlude, this maybe should help. Download and install this file:
L2Java_updates.torrent 253MB (For faster download use torrent)
L2Java_updates.exe mirror 2

P.S.S If you don't have Lineage2 Interlude client, you can download it with installed our server patch using this torrent file: L2Java_client.torrent