I havent tested this thoroughly, but it might work indoors.
I was stuck in a building in Thunder River, so I started toying with spells and I found this.
Cast Path of Asura, wait ~1 second, click your mount key, wait ~2 seconds, then jump.
When you land, you'll be mounted.
Also, if you cast Path of Asura, hit your mount key, and then jump.. You'll begin seeing normal mounting animation, but you can cancel this cast (normally you cant interrupt mounting) by hitting Esc.
I was stuck in a building in Thunder River, so I started toying with spells and I found this.
Cast Path of Asura, wait ~1 second, click your mount key, wait ~2 seconds, then jump.
When you land, you'll be mounted.
Also, if you cast Path of Asura, hit your mount key, and then jump.. You'll begin seeing normal mounting animation, but you can cancel this cast (normally you cant interrupt mounting) by hitting Esc.