TN Visa for a consultant?

I am a Chemical Technologist (Scientific Technologist under NAFTA for TN requirements). I'm being offered a job by a Canadian company to work in the U.S.
They are set up as a corporation in the U.S., but haven't yet done any business down there. They would also prefer that I work as a consultant, but are flexible.
Their immigration lawyer said I should qualify for a TN visa. But I didn't think you could get a TN visa working as a consultant. I'm also concerned that I would basically be their lone U.S. employee/consultant at this time, and that may complicate matters/confuse the immigration officer. I do not even want to try this route if I feel I have a good chance of getting denied.
Can someone tell me if a person is able to go down on a TN visa if they are a consultant?
Any other feedback would be very much appreciated.