If you use the trick posted Above you can use your regular mount in AQ40 to get around.You can mount up and ride around in Blackrock Mountain simply by standing in the ground "dirt" area before the stone ground at the entrance of BRM. Then jump onto the stone ground and hit your mount icon right when you land. Be careful when running on the chain and exiting the middle column to get to BRD as you might just run off into the lava.
Before the steps leading up to where the first boss (Skeram) would be (assuming you killed him already), if you dismount, then jump from the dirt onto the steps and mount right away, you will stay mounted and can travel all throughout the bug tunnels with your regular mount. It's really useful for getting around the instance when you haven't gotten the bug mount yet.