PStoEdit is a program by Wolfgang Glunz which uses Ghostscript to convert PostScript or PDF to an editable vector format.
PStoEdit has a DLL which can be used directly by GSview.
PStoEdit can be used from GSview 2.8 or later,
using "Edit | Convert to vector format".
For information on PStoEdit, see the PStoEdit home page at http://www.pstoedit.net/pstoedit/
To use pstoedit from GSview on Windows or OS/2, unzip the pstoedit files into c:\ghostgum\pstoedit (assuming you installed GSview to the default location c:\ghostgum\gsview).