Self-drive is easy from Kota Kinabalu with a mostly decent bitumen road and adequate sign posting. It does become mountainous and windy on approach but also very scenic. The journey from KK is about 90-100km and takes approximately 2 hours depending on how confident you are overtaking very slow trucks doing 20 km/hr. Exercise patience and caution as locals do overtake on blind corners, over double lines, and occasionally with on coming traffic.
Buses from Kota Kinabalu or Ranau are available.
Long range taxis from Kota Kinabalu or Ranau are another option.