Hi @Anonymous .
I created one setup and ran the following code.
import adsk.core, adsk.cam, os, traceback
def run(context):
ui = None
try:
app = adsk.core.Application.get()
ui = app.userInterface
doc = app.activeDocument
products = doc.products
cam = adsk.cam.CAM.cast(products.itemByProductType("CAMProductType"))
setups = cam.setups
setup = setups[0]
prms = [p for p in setup.parameters]
for prm in prms:
msg = f'{prm.name}:{prm.title}:{prm.expression}'
print(msg)
except:
if ui:
ui.messageBox('Failed:\n{}'.format(traceback.format_exc()))
It outputs a list of parameters for the setup.

The expression property of the "wcs_origin_boxPoint" parameter is
Red: 'top center'
Blue: 'top 4'
To change it to 'top 4' while it was 'top center', I ran the following code.
prm = setup.parameters.itemByName('wcs_origin_boxPoint')
prm.expression = 'top 4'
Unfortunately, I got an error and could not change it.
I guess the change in WCS is not yet supported.