I'm leveling it on my 4 DK's all at the same time. Since I'm shooting basically just for Zin'Rokh and then the Alchemy mount once my skill gets high enough, here's the "best" way I've determined to get the sword:

I start with each character at Acherus. I then put each one of them on to a flight path taking them to the nearest point to a digsite. Now, I specifically do NOT go after the Night Elf digsites. There's only two on the entire continent of Eastern Kingdoms and you're likely to only complete one or two of their projects. There's one in the north/center of Eastern Plaguelands and one in the center of Duskwood. Just don't do those digsites.

Whoever lands first I fly to their digsite and dig it up. Then I cast Deathgate while I look at the map and determine which flight point they're going to next--As soon as they get back to Acherus they're on the flight path to wherever. I then swap to the next character that has landed and then continue this until my brain turns to mush

Using this method I'm able to *usually* keep 2 guys on the flight path while I dig with another guy. It's not near as efficient as doing one character solo, but I'd say it's somewhere around 40-50% as efficient. That's good enough for me considering all the rewards are BoA. Also, a few notes for the intrepid Archaeologist:

If you're JUST going after Zin'Rokh, DO NOT COMPLETE ANY TROLL PROJECTS. Just gather the fragments from the troll sites and leave them in your bank. You can't get assigned Zin'Rokh until you're at 450 skill, so any fragments you use will be wasted--The time sink to this isn't getting to 450 skill, it's completing the average of 30 projects you'll need in order to get assigned Zin'Rokh. In this way you'll only be completing Fossil and Dwarf projects. Yes, it's ridiculously slow to level at first, but the payoff is thus:

Once you're 450 and can get assigned all the epic projects, all of the Cata zones get opened up and will have digsites in them. This means that while you're digging around Eastern Kingdoms for troll fragments trying to get your Zin'Rokh you're going to get--That's right, you guessed it--Vash'jir as a zone where you'll have digsites. Vash'jir is the worst zone in the game for Archaeology. So, do yourself a favor and just save your 1500 troll fragments you should have hitting 450 just doing Dwarf and Fossil projects.

In the end you should basically take an extra 40% more time not completing troll projects but then as soon as you hit 450 you'll A) immediately skillup to 525, and B) in the 30-40 troll projects probably get assigned Zin'rokh.

Questions?