In Acrobat, go to Preferences (Ctrl-K) and chose the Content Editing pane.
The first item allows you to change the Image Editor used for editing images. Click on that button and navigate to the directory containing the executable for Corel Photo-Paint and click on the program (a .exe file) and press OK. Then, press OK from the Preferences dialog.
Note that this does not guarantee that the image editing program will necessarily do all the correct hand-shaking with Acrobat. The interface was actually optimized for Adobe Photoshop.