You cannot use a simple jumper because the standard behavior is to turn off the PS if he power button is continuously pressed. If you look at the timing diagram on the last page, they give you a pule width of >50ms that the switch must be on. You can simulate this with a timing relay or timer IC.
Sometime after the ME_AC_PRESENT signal rises, the PWR_SW# will rise as well. You then have to hold the signal low for >50ms and release. This should turn on the power.
Hope this helps.
Regards,
Stuart Borden