Roger is a bit removed from this park, so let me interpret for him.
First of all, I have a color trail map overlay, but I don't have the actual topo map in front of me. So, what I give you for directions will get you directly to Kelly Lake, but it may not be the very best route. The lake is in the south central part of the park, so start from the Coyote Creek Entrance. You start on the Spike Jones Trail, and immediately turn off left onto the Grizzly Gulch Trail. It goes east and passes some side trails. Then turn left onto the short Dexter Trail. After 0.6 mile, you intersect the Wasno Road, and you turn left. Within a few tenths of a mile, you intersect the Kelly Lake Trail, turn right on it, and after about a mile or so on it, you should walk up on a lake on your right. That's Kelly Lake. I don't have any accurate mileages on this overlay, but it shouldn't be too much more than six miles. Somebody correct me if this is radically wrong, or if you know a better route. I've never been to that lake before, but I can read a map overlay.