Can the Uno wake a sleeping USB host PC?

In the project I'm working on, an Arduino will be connected to a host PC via USB. The host PC must be allowed to sleep if idle for some time. (By "sleep", I mean S3 power state.)

My Duemilanove can wake the host PC by sending a 20 ms low pulse through an ATmega328 digital output that I've wired to pin 6 on the FT232RL. (Pin 6 is Ring Indicator.)

Is there a similar / simple way for an Uno to wake a sleeping host PC? Or, do I have to customize the Uno's ATmega8U2 serial-to-USB program to handle this?