Your Wow server must be 3.0.3+
Go to your Database (Im using HeidiSQL - ArcEmu)
Create a new record and put a high [Entry] number.
Then put exactly what i put in
[Class]: 15 (all classes)
[Field4]: -1
[Name]: Reins of the Frostwyrm (name whatever u want)
[Displayid] is the item icon, i put the Azure Whelpling as mine.
You can put any buy/sell price. (1000000 = 100g)
[Spellid_1] is to summon the Frostwyrm.
Your done! you can do this with any mount.
Please tell me if i made any mistakes.