It seems that Tom Williams, Ian Brown, Dave Noble and Adam Darragh have done some climbing/new routing out that way, but route information is quite scarce (Dave has a few trip reports on his web page which exemplify the adventurous nature of the place.
I've actually been keen to get back that way to work on a few multi-pitch lines I was eyeing off while canyoning out there.
As to whether or not it is allowed: well, it IS national park, so it's always a dubious issue, but unless it suddenly turns into Centennial Glen, I don't think there will be too many problems.