Steven Zahm@ Jennifer
Right now, using shortcodes this is not possible. The only way this is accomplished in cMap is to edit the PHP file for the single view. I can give you instructions if you are comfortable editing PHP but at this point I would not recommend it. In a week, maybe two I will be releasing a new version of Connections which features an interactive point and click Template Customizer.
I will also be releasing an updated version of cMap, version 5.0, that take advantage of it. One of the major feature enhancements by utilizing the Template Customizer is the both the list and single views can be independently configured. What this means to you is that you can very easily without editing PHP files customize the image size for both the list view and single view.