Yes, the ST3 has hollow bars. You can even slip the wire through the rubber plug on the end of the bar. It makes for a very clean installation. Make sure the ID of the bar will allow the element to fit. I have heard that these units do not get as hot as the elements that wrap around the bar directly under the grip.
Not to change the subject, but I also have a Vrod and I was at the dealer the other day, and Harley has this display there called "heat demons". It is a inside the bar grip heater, and someone must have left them on all day as the grips and entire bars were so friggin hot you couldnt touch them (really). Im a heated glove guy, but the way they wire to Harleys is so cool, its molded into the clamp for the left master cylinder and has 4 Leds for temp indication. It looked factory not aftermarket, at least on Harley bars.