The co-ordinates are on the site as well. Just under the directions:
Get to Lynwood road and travel in an easterly direction ( towards Bronkhorstspruit) till you cross over Hans Strijdom Dr
Carry on down Lynwood for another 5.2km till you reach Boschkop Turnoff, turn left (shopping centre on right)
Continue for 2.8 km (past mooiplaats) to Tarentaal dirt road, turn left
carry on for 1.4km to T-junction, turn left and you will see The Climbing Barn on the right after 500m.
Gps co-ords: 25*47'59.19"S