It worked in versions below 4.0 (i.e. before 2007), because we had been using the Windows API to handle fonts. For platform independency - and to gain identical text layout on each supported platform - we created our own font manager. This font manager only handles fonts with True-Type contours.
Creating the font manager required about 6 months of work (including all bug-fixes). Extending it to handle PostScript outlines might require about additional 3 - 6 months. The problem is not to read the font structure, but VPE provides font subsetting for PDF export. Subsetting means that fonts embedded into PDF do only contain the glyphs that are actually used in a document, which makes the embedded fonts as small as possible. But this means to assemble on-the-fly a whole new font file, with all tables and structures conforming to the specifications. This is not a simple task, as the specifiation is huge (see
http://www.microsoft.com/typography/otspec/otff.htm - each table listed there is a link to a separate web page). It would also require to extend our PDF generator to write new PDF structures for embedded PostScript outline fonts (which are called CFF). Therefore we have currently no plans to support CFF.
Regarding your question about font conversion: quickly googling for "cff to true type conversion" yields several results. We didn't dig into it, but it looks promising. If you find a good conversion tool, please let us know here, so other users can benefit from this thread.