Tutorial for gpgsm?

[Simon Josefsson]

Is there a tutorial on using gpgsm?  I find it a tad bit difficult to
use.  For example, steps I would want described are:

* How to mark a CA certificate as trusted.

* How to import a key and bind it to some certificate already
  imported.  Alternatively, import key and certificate together, from
  a pkcs12 blob, or pkcs8 + certificate blobs, or whatever.
  Alternatively, don't import the key at all, but specify location of
  key using a parameter when signing.

* How to import a CRL

I'm trying to replace the S/MIME support in OpenSSL with gpgsm for the
MUA Gnus.

Perhaps I shouldn't be using gpgsm directly?  gpgme didn't seem to
have a command line front end.

Thanks,
Simon