From the summit the easiest approach would probably be just to take a straight line down across the heathland to the top corner of the King's Plantation, to the track over the double stile. From here continue down the track, branching left and following your GPSr to the co-ordinates.
This has got to be my favourite cache I've ever hidden - I don't want to put too much here in case I give it away! Permission has been obtained from the Forestry Board (or DEFA as they are nowadays), as it's a bit out of the ordinary - something to round off your walk with on a bang. All I'll say is that you're looking for a standard clip-lock container with a logbook, inkpad and stamp (in plastic bag) and some space for swops. I hope you enjoy finding it as much as I did making it!
To get to the cache, from part one head down the path then take the turn off to the left. Part two is near the stream which you will shortly encounter - once you're finished there, cross the water (plenty of rocks to hop about on), and pass through the gate. If you follow this footpath eastwards through the fields, you will soon arrive back where you began; I hope you enjoyed it!