So to generate keys do:
        
gpg --gen-key
        
select 2 (DSA only)

choose a key size (eg 1024)
        
don't enter any comment (not implemented comments)
        
don't enter a password. 

export the public key:
        
% gpg --export > pub.pgp

gpg doesn't seem to be able to export private keys so copy
the secret keyring with just one key in it:

% cp ~/.gnupg/secring.gpg pri.pgp
% echo hello world > junk

then sign the message with pgpdsa:

% pgpdsa -s pri.pgp junk junk.pgp

verify the message with pgpdsa:

% pgpdsa -v pub.pgp junk.pgp junk.out
% diff junk junk.out 
 
verify the message with gnuPG:

% gpg --verify junk.pgp
        
verify the message with PGP:

% pgp junk.pgp
 
and it all works.  The code needs a few leaks and buffer
overflow opportunities plugging, but this is enough
to start with.
 
To create a smaller cert, chop it off in a binary
editer 2 bytes before your userid string which
you should recognise (email address).  You don't
need userids for pgpdsa.