If your camber, castor, or KPI is off, something is bent. Find it and fix it.
If you want to set the castor to a setting other than stock, Please, please be VERY careful. The trunnion is NOT designed to take side loads. And, yes, they can shear/break/snap/bend. The only way I would adjust castor is after fitting spherical lower joints such as Canley sell.
YMMV