Hi
Creating explode lines is now made easier in Composer 2010. Simply explode the components all over and create explode line from neutral position. See attached video.
You can also change the explode line to zig-zag along XYZ axis by changing the "construction mode" property of the explode line. (not shown in the video).
Have you tried this before? Did you get the trail line you expected?
Rakesh
SolidworksComposer