If you want to create a button on the fly and have Nomads assign it to a statement label/perform, assign it to a set CTL value and then using the CTL's definition option in NOMADS define the logic you want executed.
For example in your program you can create the button with:
BUTTON 100,@(10,10,10,2)="My Button"
In the NOMADS designer, select CTLS from the toolbar or User CTLS from the Utility menu option and define your logic for CTL 100.