Hello gunspike,
The elaboration that can be done inside Photoshop thanks to the PhotoshopToSpine script is more advanced than what Spine would be able to implement in the editor, so it's better done in Photoshop itself.
The script can deal with adjustment layers, blending modes, arbitrary position of the axes thanks to the origin of the document taken into account, as well as leaving your layers modifiable in the PSD but flattened as a single layer on export. Plus, it's really easy to use.
Please have a look at the Github page as well as the youtube tutorial for a walkthrough of what it can do and how to use it:
spine-scripts/photoshop at master · EsotericSoftware/spine-scripts