Ho yus indeed!
When we found it I was totally surprised it was in a completely different place to where I thought it was! Did the whole slap-hand-on-forehead thing when I realised you could see it from the road, and the car park here: http://tinyurl.com/n2t628
From the car park, the path is pretty obvious in front of you. It's less than half a mile up a gentle slope - http://tinyurl.com/lwmxk7 - the quoit, as I recall, is visible all the way up so you can't get lost!
The castle is also extremely visible from the car park and quoit, and is well worth a visit while you're there! :)
Now where's them dead easy directions for the Bosporthennis Beehive Hut I keep meaning to post? ;)
G x