The details of the Intruder can be found in the Winter 2002 issue of Fish and Fly Magazine. They are quite detailed as while the fly is not difficult to tie, it is labour intensive. This fly is tied by its originator - Ed Ward as a "shank" fly - for a lack of a better term, one could best see how it is done from the magazine. I tie it as a tube, as I find it quite a bit easier.
I do believe in its original form Ed tied it as a regular hooked fly.
If you can't find a copy of that magazine - let me know and I'll come up with a version of the instructions for you.
Tight lines - tyler.
Still Living Large!