In September, you won't need any climbing equipment. Last time I did it in trail runners.
For route information, start here: Mountaineers Route info links within...
Some of the info is out-of-date (so the links don't work). But for all the links that do work, you will find a gold mine of information. The videos I created back in 2010 will give you a good flavor of what to expect.
Note that there are key points on the route that you need to recognize -- otherwise you could get off route and lose hours trying to figure out where to go. And note that the Mountaineers Route is NOT a trail, contrary to the Inyo National Forest's information within Recreation.gov. The route is simply a use trail, some places it is a well-beaten path, but others, you are boulder-hopping and wondering if you are on the correct route.
Study the route carefully before you head out!!! Good luck!