Follow the steps below:
There is a similar post about this, but it requires a faction change. I have logged in and out for a for a few days and it is still there.
Scroll of Resurrection = SoR
1. Send a SoR
2. Have the SoR accepted
3. Make sure a subscription is added to the returning account
4. Wait 7 days
5. Go to your battle.net account -> Click the account you sent the scroll on -> Scroll down and click "Referals & Rewards" -> Click Scroll of Ressurection -> click the history tab -> claim your mount, (read next step first).
6. Make sure you claim your mount on the opposite faction than the charecter you want the mount on, so if you want the mount on horde, send it to an alliance toon, if you want it on alliance, send it to a horde toon -> Claim Reward.
7. Wait about 15 minutes to receive the item in mail.
8. DO NOT LEARN IT (the GM made a "Exception" for me).
9. Open a ticket and tell them you sent the mount to the wrong character.
10. Wait for a response, tell them you meant to send it to "name", make sure this toon is the opposite faction.
11. The mount should be removed from your inventory, and you should have a mount in the mail on the toon you asked the GM to send the mount too.
12. It SHOULD be the opposite faction mount.
Enjoy!
I have not tested this for a horde recieving a Gryphon
I am open to constructive criticism.