Getting Journey to sign guitar for charitable event?

My sister is on the committee for an event in Dallas February 23rd for Limbs for Life, which raises money to provide prosthetic care and devices to those who cannot afford such. Anyway, I was wondering how to contact Journey to possibly donate an autographed guitar or at least sign a guitar that would be purchased for them to sign.
http://www.limbsforlife.org/events/view/47
Thanks in advance.
Tom
http://www.limbsforlife.org/events/view/47
Thanks in advance.
Tom