Here are some tips & lesssons learned I've experienced from real-world useage of SelfSSL:
here is the correct syntax for assigning the cert to a web site:
selfssl /N:cn=dev.yourdomain.com /V:3650 /S:123456789
If you omit the :cn after the /N:cn= (i.e /N:dev.yourdomain.com), it throws an error...took me a minute to figure this out.
The /V: is the validity of the certificate in days. So, for dev, I went 10 years.
The /S: is the site ID in IIS6. This is found in the metabase, or in the IIS manager.
Lastly, I had some port conflicts when I installed certificates on all my sites. For some reason, they were all trying to use the same certificate, even though I specified different site IDs in SelfSSL.
Anyhow, this was fixed simply by going to "Directory Security" > Server Certificate > [Wizard] > Replace Certificate, and selecting the correct certificates that SelfSSL had created.
Hope this helps.
Thanks,
akahara