How to hide all checkbox of a TreeViewer?

I have a TreeViewer without a Checkbox and want that the TreeViewer stays without Checkbox until I press a button. After press the button each item of this TreeViewer should have a Checkbox.

I've tried to use TreeViewer with SWT.CHECK and also CheckboxTreeViewer. The problem here is that a Checkbox is by default added to each item before I press the button. I've tried to find something to hide the Checkbox in this case but didn't have success.