Yes, you can ride on the Wailua river on Kauai, but they can't ballast the boats there for merchant towing so the wakes are small. But the experience is awesome. Yan't beat the lush, tropical scenery.
But he's asking for riding on Oahu, and Kaneohe Bay is awesome for riding, but there's no tow services anymore since my brother shut down RNR surf and ski.
Again, unless you know someone personally on the island, your only option is to contact Hawaii Sports at Koko Marina.
I've hooked up riders with pulls from WW in the past, but that's only when I'm actually there on the island, visiting my family at the time.