Epicor Purcahse Requistion To Do List Button Actions

I am fairly new to Epicor as our company as just recently deployed a few weeks ago. I have been set with a task to customize the Requisition Entry screen to which I have done with ease. I am now coming across the issue of a few different things. How do I change the button actions in the To Do List so when a dispatcher (Manager) wants to view the requisition it will lead to the customization and not the standard Req Entry screen. I know that you have to create custom buttons but I seem to be stuck on some of the code that I need to generate with the Button click action.

Any help is greatly appreciated

If your customization is to be run in all instances, set the customization on the appropriate item in Menu Maintenance.