I know several people who wanted a clearer description of this trick. He is what I came up with. I hope it is half understandable.
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Throw a sleeper.
Bring your left index finger to the side of the string closest to you, and pull it up so the string is draped over it. This is the same as the beginning of a braintwister.
Now, make a fist with all the fingers of your right hand, except the index finger. Swing the yo-yo towards you, so it swings under your right index finger, up, away, and lands on the string.
Make sure it lands on the same string the yo-yo is directly hanging from. This will be the string on the left (making a fist with your other fingers helps to pull the other string further to the right so you don't land on it by mistake).
Also don't "chop" it. By this, I mean jerking your right finger away from you to achieve the mount. The yo-yo should swing over your right finger by itself in a smooth motion.
As the yo-yo lands, pull your right hand up, and your left hand down. Remove your left finger, and the yo-yo should be hanging entirely on the right index finger, in a sort of one-handed trapeze.
This is the end of the "Split Bottom Entry" mount. Now comes the 2 underpasses (also called splits).
You will want to take your left index finger and put it into the doubled strings farthest from you. This should not be too hard, since the farthest string should be pulled to the right slighly (another good reason for the partial fist in the right hand).
Now, you will want to take your left finger, pull it down and towards you, under the yo-yo, and back up. When you are doing this, a string should temporarily leave the yo-yo groove, and then go back into the groove.
Now, your left index finger should be in-between the two nearest strings. But, besides the location of the finger, the yo-yo should be in the same position as it was before.
You should notice that your left and right index fingers are in the same spot, with your left under your right. Now, pull your right finger towards you slightly. Just enough so that you can bring your left finger to the top, so the weight of the yo-yo is supported on it.
Now, it is time for the second underpass. Since the yo-yo is now supported by your left index finger, you can do the underpass with your right finger. Take your right finger, pull it down and away from you, under the yo-yo, and back up again.
When you do the underpass, the string will leave the groove like before. But this time there are two strings coming off of your right hand. Be sure that the string that re-enters the groove is the one on the left (not the one attached to your middle finger).
Your right finger should now be farthest away from you, with a single string twisted over it. You can let that single string fall off of your right finger. If you look closely, you should see that you are now in a position similar to that of a braintwister.
The last part of the trick before the dismount is the somersault. This motion will be similar to that of the braintwister, but slightly different. Take your right index finger, and put it in-between the two strings that are left.
Now, pull your right finger back, while keeping your left in the same place. A triangle of string should be formed. Now rotate your fingers in a circle, so that the yo-yo swings towards you, up, away, and down. The somersault is done. You can always do multiple ones when you get good.
Now remove your right finger from the strings, and you will be back in a braintwister position. Now you can dismount the yo-yo using the double-skin the cat dismount.
Swing the yo-yo towards you while bringing your left hand down and away from you. The yo-yo should leave the string and go out in front of you. Now do a single inside loop, and catch the yo-yo palm up.
Hope that covers everything!
