This is not so much a cheat as a small glitch I think.
If you are riding a horse, you can walk up any mountain, no matter how steep, if you work at it a little.
Just work your horse back and forth across the slope you're trying to climb and you'll ascend little by little.
I rode Shadowmere (any horse will do though) all the way up to Dive Rock from the south and came up pretty much right on the campsite.