Probably the first documented guideline, which followed a CM study in the nuclear safety is this one.
The paper on TU Delft expert judgment database also contains a brief guideline to the CM.
An excellent book chapter which contains numerous practical matters is
- Quigley, J., Colson, A., Aspinall, W., & Cooke, R. M. (2018). Elicitation in the classical model. In Elicitation (pp. 15-36). Springer, Cham.
Decision Making Under Uncertainty: Introduction to Structured Expert Judgment by TU Delft OpenCourseWare is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at https://online-learning.tudelft.nl/courses/decision-making-under-uncertainty-introduction-to-structured-expert-judgment//.