Crush it to very small granules, soak it in compost tea and just throw it on the ground. Keep doing that. If you really want to put the work in then use a garden weasel or something to get it into the soil. Otherwise, just let worms and bugs incorporate it. It'll take longer and you'll lose some to runoff.

It's a pretty steep slope in a lot of places with a tropical rainy season. I think some type of on contour rows are needed to prevent too much runoff and keep things where they are wanted. Rows of pigeon pea, rows of comfrey. Maybe vetiver.