Well here we go...
Only to add:
I am not sure if this works on 3.0.3, because I tested this on the 3.0.8 PTR.
The only thing you need is to be a proud owner of
Reins of the Traveler's Tundra Mammoth
HowTo?
1. Mount on your Mammoth
2. Mount on your flying mount while mounted on your Mammoth ( I presume this is possible with all flying mounts, but I am not really sure... it worked for me with my Winged Steed of the Ebon Blade flying mount.
3. Dismiss /Dismount the Mammoth.
Result:
As you dismiss your Mammoth while mounted on your flying mount, the flying mount model dissappears, but you can fly 'swim' in the air, because you have the 'mount' buff on ya.
Screen or didn't happen?
1. http://i39.tinypic.com/2128sci.jpg
2. http://i43.tinypic.com/33tkv1s.jpg
3. http://i40.tinypic.com/axcmr9.jpg
4. http://i42.tinypic.com/1zxnlf9.jpg
Add#2
Now on PTR if you're mounted on the Traveler's Mammooth and jump from a high place like dalaran for example or the big tree in Crystalsong forest you don't take any fall damage nor does your Mammoth vehicle.
eNjoY