Currently, there is no type for which the CheckboxList
is displayed in-line in the Properties
You could use a property Web Editor to display it in a dialog.
Or, in Sitefinity 3.1, you could create your custom Control Editor View (Control Designer), described in the previous post.
The version 3.1 is scheduled for the end of September.
Please let us know if we are missing something or you need additional information.
the Telerik team