The only exeption is a search field of an enum in a grid. If you set multiselect to true you can select multiple enums and the search wil show all the records of the selected enums.
Unfortunately this is not possible – by definition you always only select one value of an enumeration. If you want checkboxes, you can make separate boolean attributes for each checkbox.
Edit: What is your goal with the checkboxes? Is it to store multiple values in the database, or to filter your enum values in a list, for instance?
Enumerations are typically used one at a time – an attribute cannot have two enumeration values at the same time. You could use a helper entity with your enumeration values as boolean attributes so that you can select multiple yes/no