SDS,
not to sure what styles you are trying to install but this the way I do it.
When you have the Style icon you wish to use, take a note of it's name. This must be correct in every detail.
Copy the style and paste it into -
C:\ProgramData\Adobe\Photoshop Elements\6.0\Locale\en_US\Photo Creations\layer styles
Now go to -
C:\ProgramData\Adobe\Photoshop Elements\6.0\Locale\en_US\Photo Creations Metadata\layer styles
Right Click on any file, open with Note Pad and alter to name of your style as shown
I must stress that the name must be exactly the same as the style name.
I apologise if it seems that I'm trying to teach my Grandma to suck eggs but I want to show how I do it and I've installed quite a few styles and they all show in the drop down list.
HTH.
Kev