The first thing you have to do is point PhotoImpact to your plugins folders. I have a plugins folder on my desktop. Then in that folder, I have 3 folders (commercial plugins, freebies, and plugins I don't use often). When I install a plugin, I put it in one of those folders. Ok now back to PhotoImpact LOL You need to go to File --> Preferences --> General. When the window opens, you will see a section that says Plug-ins... you browse for your plugins folder(s). That should do it. Then you need to close PI and reopen it. Then you should find your plugins under Effect. Please note that some plugins will work differently with PI (which uses Objects as layers) than with PhotoShop and others that use "real" layers.

I hope this helps