I've used a couple of private courier companies and have had nothing but great, efficient service. Only recently had the misfortune of using Speedservices and it was a total abortion.
http://www.guitarforum.co.za/off-topic-lounge/speedservices/
but thats my personal experience, others on this forum have never had a problem with them.
IMO pay the extra money and get peace of mind.
Not sure if you're asking how exactly to USE a courier service, if so, you simply ring them up, obtain a quote and they pick it up and deliver it for you.