reading the animist manifesto would be a good start...
I could see part of it being like doing group relationship counseling... it takes time to start relating to other than human persons as persons again... do this after a nature walk... then maybe a drum circle some way of honoring creation the totality of all other than human persons...

bring a stethoscope and let them listen to the heartbeat of a tree...it's how I teach the little ones about person hood and the feelings of nature...

Maybe you could explore the idea of 'journeys'. We know that other-than-human-people have their own journeys; whether it be the story of the acorn growing into an oak, or the story of a fox...
Have people meet face-to-face with a plant person, or stone person, and allow them to acknowledge the journey that the person has been on... have them really 'see' it, meditate on it, consider it's patterns and cycles. Can they see the tiny seed that the plant has grown from? And the mothers-and-grandmothers? Can they feel the dark rich earth that the seed slept within? And the stillness and quiet waiting of winter? Can they feel the whirl of seasons, years passing, heavy storms and winds, dry pached summers? Encourage them to journey up to the present year, the present day, the present moment, to sitting face-to-face with a human being.... and that human being acknowledging the journey.
Maybe this could work well with an exercise to look at the cycle of birth-growth-climax-decline-death that we notice in the seasons, the moon phases, our own lives, and the lives of all other creatures. Acknowledging this similarity, this nature-knowledge, this pure fact of existance, might just do enough to push people into a new respect and wonder for their plant-friend.. and to understand the levels on which we can relate, and communicate. I think it would be really difficult to BEGIN with the idea of Personhood, but perhaps they can be led to discover it in their own way... and that's the best way of course!