Here are some follow ups.
I have now been able to generate tool paths. It turns out I was using axis substitution correctly (at least I think so), by selecting the axis of rotation of the rotary table, in my case the X axis. I am running a rotary table on a 3-axis milling machine, rotating about the x axis.
The reason I was not getting tool paths was due to an improper "Machining Boundary" not due to an issue with my "Axis Substitution" Selection. It appears "Axis Substitution" requires a machining boundary defined by a selection, however selecting the features on my part (as I have often done for 3-axis paths) was not working in this case, leading to no tool path generation.
I still think "Axis Substitution" still needs to be explained in the HSMworks manual, as far as i can tell there is no explanation of its function in the manual at all.
I am still trying to understand proper use of the "Machining Boundary"
In the example below an Adaptive path is wrapped by selecting the shown axis in "Axis Substitution" and using the rectangular sketch as the "Machining Boundary. " The tool path stops at the boundary and does not go all the way around. Is there a more appropriate boundary condition for this?

In attempt to get the path to go all the way around I first tried extending the boundary, but this does not help (A below). The path seems constrained by the plane of the boundary rather than its size, however lowering the plane of the boundary sketch did not produce the expected result of complete wrapping of the tool path (B below).

One thing I found that works to wrap the path all the way around was manually adding "Additional Offset" to the boundary until the ends of the path overlapped (below A and B). However the path reaches the end then returns, rather then rotating continuously. Ror roughing this is not really a big deal, the rotary table just goes back and forth 360 degrees of rotation. Although in some cases the tool will retract and the table will rotate back to the starting position before the next pass effectively wasting half of the rotation time. Is there a better boundary condition that will support continuous rotation?

I was happy to learn that axis substitution is supported in pretty much all of the 3D tool paths in HSMworks. 😀
However this strategy of adding "Additional Offset" to the boundary will cause some paths to extend in the undesired direction along the x-axis, so it appears that Additional Offset is more of a work around then a ideal containment strategy, as show for the parallel path below. Again the path reverses every 360 degrees rather than rotating continuously. Continuous rotation would be preferable in certain cases.

I was also pleased to learn that the Flow tool path has an Orientation option of "Use 4-axis" that does generate true continuously rotating finishing tool paths constrained to selected surface geometry (see below). However this only seems to be an option for Flow.

NOW, I need help getting a Post Processor for the Centroid control that supports multi axis tool paths. The standard Centroid post currently available from Autodesk does not allow me to post any of these paths. 😐