24b stock rooted easiest downgrade process?

I am currently running the 24b stock rooted and would like to get TWRP installed. I understand I need to downgrade, however what is the easiest way to do so? Do I need to go all the way back to 10c stock? Then root, install recovery and update radio etc? Or can I simply downgrade to 23c?

My goal is to run the newest Skydragon and 35b bootstack by xdabbeb to have HD calling.

Thanks!