from flask.ext.admin.contrib.sqla import ModelView

# 'location' is the GeoAlchemy2 column
class FeatureView(ModelView):
    ...
    form_overrides = dict(location=WTFormsMapField)
    form_args = dict(
        location=dict(
            geometry_type='Polygon', height=500, width=500, cloudmade_api="{your_api}"
        )
    )
    ...