Fusion 360's 3+1 and 3+2 CAM are currently preview features and must be enabled by navigating to preferences and selecting the preview tab - where you can enable the Tool Orientation Feature.

With Tool Orientation enabled you will begin to see the Tool Orientation tab in each of your CAM operations, which will allow you to establish a different coordinate system relative to your initial setup.


Now with operations using an alternative tool orientation, and the fourAxis property in your post processor set to Yes, your posted files will contain a J5 command at their start which will rotate your B axis into a new tool orientation (B is ShopBot's default rotary axis). Make sure that you are maintaining continuity in your home position between tool orientations, and if the bAxisTurnsAroundX property is set to Yes, make sure that your tool orientations are moving around the X axis of your setup (this is dependent on how your indexer is oriented on your tool).
The example below was copied from a file where I used the same tool orientation as my initial setup - resulting in a B-axis move of 0:
SA
IF %(25)=1 THEN GOTO UNIT_ERROR
&PWMaterial = 3
&PWZorigin = Part Surface
' Face3
J5, , , , , 0
TR, 14000
C6
PAUSE 2
J3, 3.325, 0.1838, 0.6
J3, 3.325, 0.1838, 0.2
MS, 2, 2
M3, 3.325, 0.1838, -0.0358
...
Notice how the J5 is posted before both a C6 (spindle on) and the initial jogs to safe-Z heights - so just be careful in where your tool is located relative to your stock and indexer.
I hope the helps!