Well, you can skip this by killing Kazen Fecae with a raid (60 warrior, 2 60 clerics, 1 kiter, and 4-5 DPS will suffice).
If you don't have such a force on hand, I dunno how realistic doing a necro epic is however, the mob you seek is in the Royals area (The description you list above is for getting the herb AFTER the October 2001 Revamp of Chardok. We have the first version):
[You must be logged in to view images. Log in or Register.]
Bottom left corner is royals area. Enter the locked door into royals area (you need a Rogue with 201 Lockpick), go inward and past the second locked door (be aware of the fake floor trap at this 2nd locked door). Inside this room just behind that second locked door is the mob you are after. He stands immediately next to the false wall at the opposite side of the room from where you entered to the hallway.
(-850,+850) is his location (Y,X) coordinates based on that map.
The hallway has 4 roaming mobs that you will need to contend with at the same time, so bring an enchanter.
Once those 4 are killed, move your group to the opposite end of the hall and pet pull the herbalist through the fake wall towards your group and FD split him.
He has a 2 hourish (maybe 90min?) respawn and a place holder. He also doesn't drop the herb every time he is killed. So this is a REALLY shitty camp to sit there and try to get. It is best to either tag along with a Royals raid or join a group that is farming Royals every 2 hour.