- [Mystical Skyfire Diamond] -- This metagem can cut the time it takes to cast Tame Beast in half, and you can't tame this beast without it. You have to repeatedly cast various aspects until its special proc goes off.
Heroism or Bloodlust -- The same ability with different names for Alliance and Horde shamans; having a friend in your party use this will further reduce your taming time by 30%. If your latency is good, this should make your taming just barely fast enough to succeed.
- Mind Control -- Bring a priest friend along too, and he or she willl be able to take control of one of the Grimtotem NPCs to summon the ghost wolf whenever you're ready.
- A handy macro -- To save time in getting your casting going, just type "/target grimtotem spirit guide;" on the first line of a macro, and "/cast tame beast" on the second. Then drag it to your action bar so you can hit it repeatedly just as you ask your priest friend to summon the wolf. [Thanks Grunde!]
- [Drums of Battle] -- It's also very helpful to either be a Leatherworker, or have one in your party who will use this for you just before you start your taming, in order to shave a few more moments off your taming time.
- Be a troll -- Trolls get a Berserking ability, which might just be the final little bit you need in order to cut down the taming time enough to snatch this ghostly wolf pet. A lot of non-trolls have succeeded in taming this pet, too, of course; but if you happen to be a troll, feel free to use this ability to make it a bit easier.
After all that, you need a macro or something to immediately target the wolf and start taming the very moment it appears. Then, you can pray for a few seconds and hope everything works. It may be very hard, but it has been done before -- though one person on Mania's site said that her new ghost pet died a second after she tamed it, possibly as a residual effect of its otherwise very limited lifespan. So if you want to try it, be patient, and
[Update]: I've edited this post to include some of the other helpful information from commenters and other sources that came out after we originally published it. Be sure to check out our other resources on the Ghost Wolf pet, including a video showing the taming in action, a story about how Matthew Rossi helped his wife get one, and proof that the Grimtotem Sririt Guide will remain tamable in the future.