Notes: Openfire v3.7.1, Java 1.6, RHEL 6, StartSSL Class2 Signed Cert
The following are command line instructions for importing an existing SIGNED certificate and KEY to OpenFire.
1.) Stop Openfire.
2.) Merge your your root CA with your existing certificate:
cat example.com.cert startssl.class2.ca > example.com.TempCert
3.) Convert your existing Private Key and new merged certificate to the pkcs12 format.
(This step requires you create a password, I am going to use the default password for simplicity. "changeit")
openssl pkcs12 -export -in example.com.TempCert -inkey example.com.private -out example.com.pkcs12 -name example.com
4.) Merge your private key and cert to OpenFire's private Keystore.
keytool -importkeystore -deststorepass changeit -destkeypass changeit -destkeystore /opt/openfire/resources/security/keystore -srckeystore example.com.pkcs12 -srcstoretype PKCS12 -srcstorepass changeit -alias example.com
5.) Start OpenFire
Figuring this out took me forever. I hope it helps some one else too!