Quests are mostly hardcoded.In some cases, you can change the items in them and how they are used...and hex editing the .dll files might allow you to alter how much a quest offers in terms of reward (for example, how many levels you canget from the Book of Skill, how many sockets you get in Act V, etc.).
But adding entirely new ones really is beyond our grasp...at least officially. I mean, I added some scrolling text to a few NPCs' speeches (just text...no audio) that points players toward finding something they need that I "hid" in one of the towns.
Some people have made it so that Khalim's Will drops in Kurast already completed and ready to break the Compelling Orb...which frees up three other quests if you want to make the body parts of Khalim do something more useful than be part of a Cube recipe.Other people have removed the Compelling Orb completely and thus eliminated the need for the Khalim quest at all.
You could also perhaps have special items that drop from specific monsters and have those become "unofficial" quests...perhaps gathering pieces that in the Cube can become some uber-item or something. You could have clues drop in various places in the game so that people know what to look for.
But again, actually changing or adding to "official" game quests is...as far as I know...currently not very feasible.
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- JEFF
"A hero is no braver than anyone else. He is only brave five minutes longer."
For my latest mod (for LoD/expansion), download at http://www.fileplanet.com/dl/dl.asp?/planetdiablo/phrozenkeep/mods/sic_beta.zip - Or for old stuff (for classic D2), visit my orignal mod site at www.planetdiablo.com/sanctuary