How to install a new server ssl certificate with chain certificate

Jephe Wu -

Environment: CentOS 5.5 32bit web server with Apache httpd installed. We need to renew one of ssl certificate for our client.
Objective: apply for new ssl cert without shutting down server

1) preparing csr file for submit to CA
2) configure new cert file and sslcertificatechainfile directive in Apache
3) run command 'kill -USR1 ppid_of_httpd'
4) use 'stat' command to check if new cert files being read (compare file access time before and after running stat)
5) use browser to check server certificate information to confirm new cert has been placed.