Someone's been lying to you. This has been a popular feature request, but currently, there's no API that will allow 3rd parties to drive the audio mixer faders in Premiere. The only control you can get is with devices like the Shuttle Pro, where you're basically emulating keyboard commands, so you can do basic job/shuttle type operations.
(Check Soundbooth/Audition though, I think they do have support for control surfaces)
I've been campaigning for a "baby-step" in that direction with PrPro's Audio Mixer. I just want to be able to "gang" several sliders, to not have to go through a Sub-mix, like one can with a physical mixing console. Obviously, the Sub-mix and then the use of the automation of its Send is good enough for Adobe, and does work for me too - just would like to do it without that need. Oh well, I can easily live with Sub-mixes.
I just wonder how hard it would be to add support for the Mackie Universal Control Protocol. Final Cut Pro apparently has it because you can use Mackie's controllers in FCP!
Mackie makes some great controllers and even the other controller brands I've been checking out offer Mackie universal controller protocol support!
Adobe would definitely make me happy if they supported a few more professional options like this.
That would be a question that Adobe could answer. I'd suggest the Feature Request route, and hope.