Mark, thanks for pointing this out.
Right now only windows has been tested, but at first glance this does appear to work. The only quirk on the system (Windows Server 2008 R2 64bit / Oracle 11.2.0.2 64bit) that I have been testing this on is, it appears that the EXTPROC_DLL values need to be escaped ('\' needs to be '\\'). As in, adding the following entries to the extproc.ora file appear to work:
EXTPROC=ANY
EXTPROC=C:\\ArcGIS\\ArcSDE\\.....st_shapelib.dll
EXTPROC=ONLY:C:\\ArcGIS\\ArcSDE\\.....st_shapelib.dll
We will continue testing this, and if successful update our documentation.
Thanks again for bringing this to my attention.
Travis