Hi,
I have used this trail for the last 5 years, since I heard about it. This is a great short cut and a good trail. I think this is used by the rangers.
We have had some strange looks when we take pictures at the "Portal trail" sign then hop back in the truck and drive around the corner.
On the turn around the pond, just before the parking lot, look for a very large angular rock,(this is due west of the pond), walk behind it to find the trail. Many switchbacks and you end up at the first turn above Lone Pine Creek.
This trail took me awhile to find and I tried several times from the top, but was afraid I would walk down the wrong trail. So I looked for it from the bottom and finally found it.
Good luck,
Bill
