Create a CSR , I find Digicert Util is the easiest way to do this
Save the CSR request somewhere on a network available to the SBS server
Run this on the SBS server
certreq.exe -submit -attrib "CertificateTemplate:WebServer" %locationofcsrfiles%\csr.txt
Save to .cer file somewhere then import this into the server via the Digicert Util
Change the IIS Bindings to this nearly imported CERT
Trackback from your site.