Hi Bruce,
I think this could be done with profiling (see http://www.sagehill.net/docbookxsl/Profiling.html). There are several profiling attributes but I think you should use
"condition". You could add the paragraphs for your slices to your files
and apply "condition="<whatever>" to them. By the way: it is not a good
idea to use the attribute "role" for profiling (see http://www.sagehill.net/docbookxsl/ProfilingWithRole.html).
This might work but I have no real experience with profiling under
docbook. I used the profiling feature with other tools (esp. FrameMaker)
and there it is used for things exactly like this. Perhaps it's worth a
try :-) ...
HTH
Thomas Gier
Technical Writer
Cologne/Germany