1] Travel to karazhan in Deadwind pass. You will receive 2 quests here. Complete those two quests in the direct area and you will be sent to Dalaran.
2] Travel to Dalaran, speak to the guy you need to (he's on the other side of the bubble from the town) and you will be sent to Shattrah.
3] Go and speak to Kadghar in the centre of Shattrah (who you started the tour with and who you decided which faction you wanted to be) and he will send you to get the first key fragment from Shadow Labyrinth (need to killl Murmur at the end and its in a pot near him).
4] Go back to Kadghar in Shattrah and he will give you a quest to get the 2nd and 3rd key shards. The 2nd key shard will require you to travel to The Steamvault in Coilfang Reservoir and is located in the deep pool of water near the first boss. You will find it in the corner at the bottom of the pool.
5] If your group has the key to Arcatraz then skip this and go straight to 6. If not then follow this. First you must obtain the quest from Area 52 called "Warp-Raider Nesaad". Go and kill him and return to the quest giver. Then you will be sent to Eco dome mid-realm where you will be given the task of collecting 10 surveying equipment boxes. Return to the quest giver. you will then be sent to Nexus-Prince Haramad in Stormspire who will ask you to locate triangulation point using his device (Co-ords 66,33) and then deliver to Dealer Hazzin at the protectorate watchpost. Then you will be asked to discover Triangulation point 2 (co-ords 28,41) and hand in to Wind Trader Tuluman at small trading point back across the bridge. Then you will be asked to go kill the elite demon at 53,21 (very easy tbh, can be 2 manned if not solo'd) to complete the full triangle and to recover the Ata'mal Crystal. Take this crystal to Nexus-Prince Haramad and you will be ambushed by 3 blood elves...dont worry, the Ethereals annhiliate them for you. Then take the portal where Nexus-Prince came from during the blood elf attack to Shattrah and speak to A'dal in the Terace of Light in Shattrah. Now you will be given the quest to obtain the Arcatraz Key shards. The Top Half of the Arcatraz key can be located in The Botanica of Tempest Keep (left floating island) and drops from Warp Splinter, the final boss, and the Bottom half of the key drops from Pathaleon the Calculator in The Mechanar of Tempest Keep (right floating island). - BE WARNED : IF YOU WIPE ON THE LAST BOSS OF THE MECHANAR OR THE WAVES OF MOBS BEFORE HIM THE DOOR WILL BUG AND WILL NOT REOPEN EVEN WHEN YOU RUN BACK. TO AVOID THIS, TAKE A WARLOCK FOR SOULSTONE OR YOU'LL HAVE TO PAGE A GM AND HOPE THEY GET BACK TO YOU QUICK ENOUGH AND ARE WILLING TO PORTAL YOU TO THE OTHER SIDE (as of 06/02/07). Once you have both key shards take them back to A'dal in Shattrah and you will have your Arcatraz key.
6] The third fragment of the Karazhan key can be found in The Arcatraz of Tempest Keep. You aren't required to kill any bosses if your group chooses not to and you will find the key shard in the room where you first encounter voidwalkers. This room is the first room you come to after you go up the "glass" ramp in the first boss room. As you enter the voidwalker room, the shard is found to the immediate right in the corner of the room.
7] Now you have the 2nd and 3rd key fragments, return to Shattrah, hand them in and you will be sent to The Black Morass (aka The dark Portal) in the Caverns of Time and you will need speak to Medivh to activate your key. However this means completing the Black Morass event. This event will require you to kill elites that spawn from portals whilst protecting Medivh whilst he opens the dark portal. From every 6th portal a boss will spawn. After the 18th portal the dark portal will open and the task is complete. You can now speak to Medivh and claim your Master Key to Karazhan. At this point return to Kadgar in Shattrah. **NB - TO ENTER THE BLACK MORASS, YOU MUST HAVE COMPLETED OLD HILLSBRAD (THE DURNHOLDE) IN THE CAVERNS OF TIME BY RESCUING THRALL. UNTIL YOU HAVE DONE SO, YOU WILL NOT BE ABLE TO START THE BLACK MORASS QUEST AND THUS WONT BE ABLE TO FIND MEDIVH.
8] Once you have returned to Khadghar you will be sent back to Karazhan where your Karazhan quests will begin!
Congratulations! You are now attuned to Karazhan!!
I played Classic until I was nearly level 60. It needs The Burning Crusade really for me though. I am lurking around Daggerspine again for a while, trying to get used to the changes lol