yes you will still need AC power to the printer.
[can you just splice the existing cable by using a parallel female to USB male cable?.... No].
Ive not seen a gender changer for parallel to usb but if it works like this cable ( see link ) then there should be no problem, i appreciate new gizmos are appearing all the time so maybe there is one.
Theres supposed to be a limit of 5 Metres (15ft?) for usb cables, then you have to use a usb repeater.
(ps ive used these in the past with no problems except for driver issues with vista.)
lol T.R.A :)