How to customize 3rd party dictionary forms

Hi,

I would like to know how to do customization in the 3rd party dictionary forms. For example, if I want to show the "Hello word!" message when clicking the button in the manufacturing MO entry window. So I need to add a button on the MO entry window and then have to write a script in the button change event. MO entry window is a 3rd party window, because of this I am not able to use the default method to customize the dictionary. I don't know how to do, these kind of customization. Please help me.

Thanks,

Manikandan