The Knox Mountain Hillclimb is run under the sanction of the CACC - Confederation of Car Clubs and the General Competition Rules (GCR's). You can find a current version of these at this link.
Be sure also to check the Supplementary Rules (2017) at this link.
See the car classification description here
Additional requirements will include a valid Driver's Licence and a valid Competition Licence.
Competition race licences are obtained through CACC, follow this link for applications. Questions can be directed to Sheree Wall at firstname.lastname@example.org