It's not called readonly. In config.py just mark the deck as analyze with no enable flag:
Code:
# Model overrides can only override the entries marked above. 2nd priority
model_overrides = {
'subs2srs': { 'enabled':True },
'Japanese Sentences': { 'analyze':True },
'Japanese Legacy MCD': { 'analyze':True },
'Japanese MCD': { 'analyze':True, 'morph_fields': [u'Text'] },
}