Autofocus assignment

Aloha folks. New here and was wondering if the autofocus on an EPL1 can be assigned to anything other than half pressed shutter. I shoot mostly underwtaer and I'm currently using a G11 and the OEM housing. Sometimes it's hard to feel halfway on the shutter button through gloves and the housing. I think if I could assign it to another button (like I can on my K2000) it'd be much easier. Thanks in advance for any help