From a SSH login on the server run:
# cd /home
# wget -N http://httpupdate.cpanel.net/latest
# sh latest
Once the install is finished you should be able to login to WHM on the Address: https://[Your IP]:2087 and cPanel on https://[Your IP]:2083
If you need to ever restart WHM/cPanel you can do so from a SSH prompt on the sever and enter in:
# /etc/init.d/cpanel restart