Third party SSL certificates, CA & Co

hallo,

having third party ssl certifikates (crt- and key-file, thawte) is it possible to

a) create a ca database and sign it with this certificate or

b) sign a existing (self certificated) ca?

my goal is to have an application to create trusted certificates which can be imported into the notes clients to encrypt internet mails.

am I right so far with my idea?

if you have some handy tutorial not the hell of a notes help…

p.s. which role should have a certificate to sign a ca?

thanks,

robert