i don't think they have an option to do that. The point of the track specific volume is to equalize tracks that originally had different volumes, which gets annoying when you work in a store and the cd playing gets louder all of a sudden to the point that you can't hear the customers.
I don't think it was intended to simply increase the max volume of your computer.
I don't like the volume control on my CRT iMac. For one thing, the max sometimes ain't all that loud, and most annoyingly, the difference between mute and the lowest volume is huge. Its either pretty loud or silent, nothing in between, unless i use application-specific volume controls.