Blessed's Comments

Got mine today.  Took about 2 hours during midsummer event.  350 of the Midsummer tokens.  Quickest way to get 100 of them is to do other factions capital cities.  Click the blue flame in the capital city.  You get an item in your back.  Click the item to start a quest.  Turn that back in at your factions home city for 25 tokens.  4 cities x 25 each is 100.  Got the rest from flying to the other outposts.  Used free Zygor holiday addon.  Pet comes in green.  You'll need an elemental stone to make the pet rare.

Confirmed as of March 2015, merging a very old account to your battle.net account still triggered the mechanics for getting this pet.  How long it lasts, I don't know.

I happened to have a 2004 vanilla account where I tried out wow way back when.  I kept playing EverQuest.  When I came back to wow in 2010, I forgot about that account and created a new one.

I came across the original CD key from my 2004 vanilla account and scanned it, opened up a web a ticket and attached CD scan.  GM verified same person old and new account.  GM linked the accounts but set expectations for no Mr. Chilly because that the promo had expired.  I logged into my main acct.  No mail.  I logged in my really old account.  No mail.  However, after logging back in to my main account again, this time I had mail!  Mr. Chilly!!!

Good luck in the hunt for this pet.