As I've wrote above:
(This is for Pagestream4, but in Pagestream3 it's similar, and yes, I used PS as shortcut for Pagestream)

1. All Fonts in Pagestream directory:

Work:PageStream4/Fonts> dir

SerialsFonts (dir)
IQEfonts (dir)
StudioFonts (dir)
SoftLogikFonts (dir)
StandardFonts (dir)
Intellifonts (dir)
Intellifonts.info IQEfonts.info
SerialsFonts.info SoftLogikFonts.info
StandardFonts.info StudioFonts.info

Work:PageStream4/Fonts>



2. User-Startup:

; PageStream4
Assign PageStream: "Work:PageStream4"
Assign PageStream3: "Work:PageStream4"
Assign PageStream4: "Work:PageStream4"
Assign SoftLogik: "PageStream:SoftLogik"
Assign Fonts: "PageStream:SoftLogik/Fonts" ADD

3. Fontprefs in Pagestream:

Fonts/Intellifonts
Fonts/IQEfonts
Fonts/Serialfonts
Fonts/Softlogikfonts
Fonts/Standardfonts
Fonts/Studiofonts
FONTS:_Truetype

---> Notice: No semicolon for fonts located in Pagestream/Fonts-directory! With semicolon Pagestream is searching in the global font-directory.....

In my case I have now more than 120 usable fonts.....