No special access issues
There are no general access issues, but in the high summer people are generally not allowed to be in this part due to the risk of forest fire. Cops close the road entrance and firefighters fly with drones 24/7 in the area. Its still possible to enter on foot but you do this on your own risk.
Park your car in Kalopoula, the kafenio that you find on the road to the top of Ymittos. You can also park further up, in the entrance to the dirt road that goes under the block. On this dirt road, in the first inner "corner" of the road, are some washed out stones on the left side of the road. There starts the path to follow up to the crag. It is a bit of a steep path that is a mtb-track. Follow this path in a few turns (3 in total) until you find yourself again on flat ground (and a straight path), like you are on a big shelf in the mountain. You find the crag after another 40 to 50 m on the path, on the right hand side behind some trees. Look for the rocks that are hidden there.