I guess you are referring to the "Power on/off" button on the top of the phone? If that is what your talking about, NO you cannot change it (to the best of my knowledge that is). If you keep hitting it, let me follow Steve Jobs @ Apples advice, "Change the way you hold your phone", lol.... You may want to look into using your Blu-Tooth headset or wired headset more often. I do as it is just easier all the way around and I get better call quality (I use either the wired ear buds that came with it or my Razer Moray+ headset)...
When it comes to listening to music though I love to use my Razer Moray+ headset. Great sound and can handle calls that come in as well..