Explain more of the build system.

README

@@ -3,23 +3,36 @@
 
              !!!! THIS IS WORK IN PROGRESS !!!
 
-If you want to hack on it, start with one of the tests/t-foo programs.
-You need the latest CVS version of GnuPG 1.0, see
-http://www.gnupg.org/cvs-access.html .  
+If you want to hack on it, start with one of the `tests/t-foo'
+programs.
 
-You need at least GnuPG 1.0.6  (but don't use a 1.1.x version).
+For support of the OpenPGP protocol (default), you need the latest CVS
+version of GnuPG 1.0, see `http://www.gnupg.org/cvs-access.html'.
 
+You need at least GnuPG 1.0.6, but don't use a 1.1.x version.
 
-To build the W32 version, use 
-./autogen.sh --build-w32
+If configure can't find the `gpg' binary in your path, you can specify
+the location with the --with-gpg=/path/to/gpg argument to configure.
 
+For support of the CMS (Cryptographic Message Syntax) protocol, you
+need the latest CVS version of GpgSM, module name `newpg' at
+`:pserver:anoncvs@cvs.gnupg.org:/cvs/aegypten'.
+
+If configure can't find the `gpgsm' binary in your path, you can
+specify the location with the --with-gpgsm=/path/to/gpgsm argument to
+configure.
+
+To enable the CryptPlug GPGME PlugIn for both protocols, use the
+`--enable-gpgmeplug' option to the configure script.  `gpgmeplug' is
+experimental and you should not assume that it will stay with gpgme.
+
+Before building the CVS version following the generic install
+instructions in `INSTALL', you need to set up the build scripts with
+`./autogen.sh'.  To build the W32 version, use `./autogen.sh
+--build-w32'.
 
 Please subscribe to the gnupg-devel@gnupg.org mailing list if you want
-to do serious work. 
-
-
-gpgmeplug/ is experimental and you should not assume that it will stay
-with gpgme.
+to do serious work.