To answer Jim's question, you need:
1. 50 hours PIC in multi;
2. At least 10 of those 50 in the type of aircraft to be instructed on;
3. A Grade 2 instructor rating (at least 250 instructional hours);
4. A twin-training approval (gained by briefings and flight test).
What spanwiseflow was referring to was the fact that in oz, people with 500 multi are unfortunately in better (higher paid) jobs than the average flight instructor.
