There are two types of text fields in the SlideShowPro Player — General, and Headers. You can use any "system" or custom typeface for these fields.
Type families are assigned through TYPEFACE/General and TYPEFACE/Headers. By default, both are assigned typeface families that are universally available on end-user's computers. The SlideShowPro Player will use whichever typeface in the descending, comma-separated list of font names it finds first.
For a more stylized look, you may embed two non-system typefaces. You would chose this option if you wanted to use bitmap fonts, or a unique TrueType / PostScript font.
Open the Library panel (Window > Library). Click the button in the upper-right corner to open the options menu. Select "New Font". A new window named "Font Symbol Properties" will appear. Click the double-arrow button to the right of the "Font:" field. Select the name of the font. Then give your font a name in the "Name:" field. Leave all other options alone. Click OK.
Right-click on the font in the Library and select "Linkage..." from the contextual menu. The "Linkage Properties" dialog will appear (see left). Toggle on the "Export for ActionScript" button.
If you are using the AS2 version of the component, the "Identifier:" field will fill with the name of your font. If AS3, the "Class: field will.
"Export in first frame" will also be automatically selected — leave this on. Click OK. If you are using the AS3 version, a dialog may appear noting that "A definition for this class could not be found in the class path, so one will be automatically generated in the SWF upon export." Click OK again.
With your instance of the component selected on the Stage, open the Component Inspector and enter the name of your font into either the TYPEFACE/General or TYPEFACE/Headers text fields. Then set TYPEFACE/Embed to True. If you want to use the same face for all text fields, simply re-enter the linkage name in the applicable typeface field.
You're done! Publish a new movie, and your custom typefaces should appear.