The last time I did it we started at Bullpot Farm, then went up Crag Hill, and around to Great Coum, and onto Gragareth. We descended to Leck Fell House and then along to Leck Beck Head, and back to Bullpot Farm.
Total distance was 9.5 miles with 1800ft ascent, and it took us about 4 hours.
Be aware though, it's very, very wet up on Gragareth.
Well what I did back in 2006 was out of Dent on the path by flinter gill then, once out the woods, basically cross country to Combe/Crag hill and along to Gragerath. The ground underfoot doing that seemed reasonable enough but it was of course very warm that summer!
Can then go off right past Leck fell house to have a look at Ease gill Kirk then up Barbondale. Or find a way back over onto the Kingsdale/Deepdale road actually. Either route back very worthwhile, if maybe too much overall.
What I actually did was climb straight up the Barbondale side of Calf top - not entirely smart - then, on the way to Sedbergh, contrived to come down rather closer to Combe scar than ideal
The shortest route would I guess start from somewhere near the top of the Kingsdale/Deepdale road. Unsure if/where you can park there though.
There's plenty of parking at Cluntering Gill Bridge, on the minor road from Dentdale to Ingleton. From there, walk along the road a bit towards Ingleton, then cut off up the hill by Yordas Cave -- there's a bit of a path by a very impressive dry stone wall that takes you almost to the top of Gragareth. Then head along by the wall to Great Coum and Crag Hill (which is the actual top). One option from there is to drop off Great Coum beside a wall (no path here) that takes you down to the track/continuous boggy rut which wends it way back to the road you started from. Alternatively, head back along the ridge from Great Coum and drop straight back to you starting point, so avoiding the fairly horrendous track and a bit of road walking.