The skatepark in Hillerød has gotten worse, since the local skaters (including myself) has moved to Copenhagen or away from Hillerød. So the street area is not something you want to go to Hillerød for. The miniramp on the other hand is pretty good. It is a medium sized vert ramp that has been cut down. So it has a fairly big transitition.
If you go to Hillerød by train, go down Milnersvej, and you will be there after 5-10 minutes walk. You have to look out for a sign that leads to the Svømmehallen (Indoor swimmingpool). If you go down this road (at a big parking lot), you will come right to the spot. If you are going by car, get off the highway at Hillerød Ø, follow the road towards Hillerød C. At the roundabout, take the first turn (right) towards the gas station. Now look out for a sign saying Svømmehallen or Frederiksborgcentret. The skatepark is in this area (on the edge of the parking lot)