Password protection on my Sony Ericsson W580i?

I want to put a password on my Sony Ericsson W580i. Normally this setting would be found in the Security setting of a cell phone and through the 'locks' section. But in there they don't have a lock to do what I want it to do. It just has the lock for my SIM card and my phone when other people try to put a SIM card in. But I want to lock my phone so everytime I slide it open or want to use it I have to type in a password.
Any way to do this?
I called Rogers and they didn't help me at all. They told me to take it to a store. I have none nearby.