Had trouble doing this the manual way, so had to firgure out some way to make this work. Anyway found out how to do this, I have Vista Ult. so this should work for all Vista users. I didn't move anything around other than my Theme folder, so make sure your folders match mine or this may not work for you.

Ok simple way to install for Vista users! Open your Limewire 4.18.8, then search "Limewire black theme", or "Limewire pink and black theme" and so on (make sure your themes have the "lwtp" ext.). Then double click, a box will appear "yes - no - cancel", click yes, wait for dwnld to finish. It will ask if you would like to use this as your current theme, either yes or no will work. Go to C:/YourName/LimeWire/ inside this folder is where your new themes downloaded, cut all of these to Documents folder/LimeWire/New Themes. When you open your LimeWire and go to View/Apply Skins/Refresh Skins (may or may not have to do this), all new themes should be viewable.

Hope this was simple enough to follow.