Instructing is a very individual, very personal thing.
Why not take some time and sit down over lunch to talk instruments, and find out what this person needs? Find out the individual's experience, recency of experience, and comfort level. Equipment flown, type of flying done, etc. Then tailor your competency check to the student.
You need to accomplish several things during the exercise. One is that you need to ensure the individual receives adequate training and review. That's a personal issue for the student. The second thing is that you must be convinced yourself that the student may be let go with your signature as the stamp of approval in his or her logbook. The third thing is that your review should cover enough basic instrument skills and practices to be considered thorough.
He or she may be reasonably expeirenced, but may not have flown an NDB approach in a while. If flying a typical ILS is a hum-ho experience, then concentrate on things that are not. You don't need to give the person an inverted back course ILS with one engine out and smoke in the cockpit, to give a good proficiency or competency check. You don't need to re-educate them or make them over in your image...just find out their needs, and then meet them. Treat it like a regular flight review on instruments.
You need to do whatever is necessary to satisfy both of you that the review has been complete. Bear in mind, and ensure the student understands before you begin, that completion of one flight is not an automatic end to the review. If the student needs more work, let the student know up front that the completion time and expense is entirely upon the student; do well, finish shorter time, but that the exercise will be flown to proficiency. It's not just punching numbers or checking boxes. Tell the individual that the endorsement comes after you're both satisifed with the progress and performance, and to anticipate that. Also ensure that any extra time isn't viewed as a punishment, but a positive thing that benifits the individual.
Forget a syllabus or a canned program; treat the student like an individual, and administer your training accordingly.