I was taught some triage as part of an industrial first aid course for working in refineries. They called it multiple casualty scene response or something like that.
In USA triage is also taught through FEMA to Community Emergency Response Teams (CERT) and you can find more information here.
http://www.citizencorps.gov/cert/about.shtmThey include contact information and training material.
The Triage teaching unit is in the instructors manual under emergency medical (part 1).
For somebody living in USA CERT would be a good way of getting a pretty good bit of training really cheaply.
Just as an after-note:
There are a lot of different forms of triage and they almost all have different priorities.
One of them might base the priorities on who is likely to survive, ie severity of injury.
Another triage system might base priority on how important it is to transport them to treatment instead of treating them right where they are.
A third might be based on what you can effectively treat with what you have right there, and who is more likely to die before help arrives without any treatment.
Triage as applied in a hospital ER and triage as applied by EMT are horses of different colours. They have different priorities and different resources.
START is likely the first triage training program to be directed at civilian EMT and First Responders. It was developed for responders to earthquakes in California.
The one thing about field triage is that it is an assessment system. You need to assess how serious all of the injuries are.
You can't stop and freeze on any one survivor because the next one might be even more critical.