Come to the session prepared. You need to have downloaded your footage and to begun to put a rough edit together. The idea of the workshop is to refine your edit and finsh the day with something closer to your final 1 minute piece.
The i movie in depth Tutorial by Ken Stone can be found at: Ken Stone .net
This tutorial goes into considerable depth about the precision editing tools to be found in imovie. Trim tools, clip adjustments, picture in picture, b roll cutuaways etc.
Study it closely and you should be able to achieve all, or close to what you need.