I haven't been that way for years, but we essentially followed the USFS Inyo NF map, with good knowledge before hand. I don't recall any road names or route designations, but there may be some up now. Pass McMurtry Meadows by the road of the same name, then head east, crossing a 6" high pipe, paralleling a fenceline (the private land), then heading back west along the main Red Lake Trailhead road. The trailhead had been signed, but little work is done on this trail. The older maps are wrong, and some websites have the real descriptions posted.
By now, this may be all changed, so I hope you get some luck with directions from someone who has down this recently.
And there's only one Red whatever trailhead in the vicinity that I know of.
The trail is rough, and it is at low elevation, so don't start out late (like we did once, with 90 degree temps and packs to carry). Split is a beautiful peak, with some easy class 3 to get to the Sierra Crest. Be careful not to dislodge rocks, or wear helmets. Do a search on "split mountain." I'm sure there's plenty of good info on the Web, somewhere.