My daughter, Lauren chews spearmint gum when she is nauseous and drinks ginger ale as well. Compazine usually works if she takes it early in the game. If not, the gum usually helps, but sometimes she just gets sick and then feels better. I agree with Eli in that your Dad needs to take his anti nausea meds combined with the natural ones. I don't think the natural remedies would work in place of the nausea meds. They would be better used with them if needed.

BUT...

She used it in addition to pills (Zofran, Compazine) not instead of them.

As much as your dad dislikes pills, they may be necessary. Natural remedies alone may be not enough to control chemo nausea.

Accupressure works for some:

Most pharmacies carry wristbands with snaps or buttons.   These wristbands are designed to press against pressure points in your wrist.
You can also try to do this by bending your wrist and measure three finger lengths of your forearm. Depending on the size of your finger, you may have to try to find the pressure  point.  Feel around with light pressure until you find a tender spot.  This is the P5 point.  The P6 point is about 1 ½ fingers back toward your wrist.   You must apply some pressure hard enough to feel it, but not too hard causing pain. 
Press on these spots for 1 minute and repeat 2 or 3 times, resting 30 seconds between each application. 

Please know that results vary and given the severity of nausea caused by chemotherapy, sticking to what works well chemically might be best. 

Hugs,
Marion

Susie