Disable the Ok button alongwith Cancel button with disableOk or disableConfirm to use only Custom Buttons.

[Bhoite96]

Else please add documentation to how I can customize the default Ok button to change its css inorder to match all other buttons in on my site.

[diegoddox]

All the docs are updated in regard to disabling buttons, when it comes to CSS I believe you should be able to override the existing by targeting the class of the element/button