Customizing an association list with defcustom to allow user modifications

I am comfortable using defcustom to define variables that hold string 
or symbol values. However, I find it challenging to understand how to 
use defcustom for a variable that is an alist (association list), where 
users can modify the entries.

For example, suppose I define an alist variable like this:

(setq mylist (list (cons 'name "Pandu") (cons 'activation 'dual)))

Now, I want to allow users to change the values of each entry in mylist 
through customization. How can I set this up so that users can easily 
modify these entries in the customization interface?  What would users
have to do?