I have seen some asking questions about modifying the power button or having one external, etc. I am no genius or claiming to be one, but I thought this article might be a good reference point for modding the power button. Its used as a guide for people who do case mods, which is make a computer case out of some weird item with the components inside (for those who dont know).
http://case-mods.linear1.org/case-mod-101-the-atx-power-switch-demystified/