Well, in case anyone else is having issues with this...
When GIF-X 2 is installing, it asks if you are using a Photoshop compatible program. If you do not have one, it says to click "Ignore." If you do, then you must select the proper plug-ins folder for the application you do have. If you don't, then you click ignore.
If you've chosen "Ignore," then to set up GIF Animator 5 (GA 5) to use GIF-X 2.0, you must open GA 5. Click File, Preferences... Go to the Plugins tab.
Select the folder "C:\Program Files\Ulead GIF-X.Plugin 2.0\Aps"
Click OK, and close GA 5, then reopen GA 5. GIF-X 2 will now be listed under "Ulead" when you click on "Filters" in GIF Animator 5.
The ReadMe file for GIF-X 2 states:
"You can add Ulead GIF-X.Plugin 2.0 into your image editor (Adobe
Photoshop, Paint Shop Pro, Ulead PhotoImpact, Ulead GIF Animator, etc.)
by pointing the plug-in folder to GIF-X.Plugin 2.0\APS or copying the
AniGif2.8bf file under GIF-X.Plugin 2.0\APS to the plug-in folder of
the image editor."