Hi ryod,
Not very user friendly indeed, the Output(s) computation option corresponds to the "disabled" tag present in the "root" tag of a "graph" in the .sbs file:
<graph>
...
<root>
<disabled v="1"/>
...
</root>
</graph>
In Pysbs, once you have created a SBSDocument on the concerned .sbs, parsed it, and get the SBSGraph you want to edit, you can do:
my_graph.mRoot.mDisabled = '1'