You will need

1 1/2 pint of leaves  and spines crushed

1 quart of 80-100 proof vodka or alcohol of your choice

Place you crushed leaves and spines in a quart jar, it should be about 3/4 full

Cover with the alcohol until you have about an 1 of headspace

Cover tightly and place in a sunny window and let steep for 4-6 weeks shaking every day or two

Strain through a fine sieve to remove any plant material.

Store in a cool dark place for up to 7 years.

Since Honey Locust is a mild laxative, dosing should be low.  I found no guidelines on any dosage at all so start low at 

.5 ml. Microdosing when you are trying to treat cancer seems silly but smaller doses will allow your body to see what effect it has.

You can also buy a tincture that has dosing on it to be sure that you are receiving the correct amount.