Has anyone had any success modeling the tire using car sim. We currently have the new round 3 tire data from the tire consortium, however, I am unsure of how to get started in accurately putting the model into car sim.

you'll probably find you'll need the add on program suspensionSIM to do any modelling in CARSIM.
I'm guessing you haven't tried contacting them because they are usually quite helpful and willing to lend a hand with any issues and what not.

If you have access to the Pacejka coefficients, Carsim 7.1 has a Pacejka tire model input. Or you can use the long,lat, and aligning torque curves to input in a Internal with Camber Ext. model.

Hmm, you should consider if it is necessary to put a new tire model into carsim.
What do you want to achieve/measure with it? If you need a loadspectrum, the implemented Michelin F3 tire model is accurate enough. The same if you need to calculate maximal tire forces.
If you don't know exactly your mass intertias, CG etc it isn't worth to implement a new tire model. There are so many factors you need to know correctly and which can't simply be taken from CAD. What about the moving driver, what about swapping liquids, inner friction and so on.

I would recommend to waste your time on real testing with an adjustable suspension. Forces can be calculated analytically.

Or to say it in the words of Claude (what he told me a time ago):
"Bah, dynamic computer simulations, garbage in, garbage out! Use our sense, this crap is just another way of brain masturbation."

There's also the issue of whether or not the belt surface at calspan is an accurate representation of what your car is actually driving on at competition.

To the original poster: CarSim 7.0 and 7.1 will accept Pacejka coefficients.

Obviously no simulation is going to be perfect, however simulation prior to the ability of physical testing is beneficial. If it wasn't all major motorsports teams would not be spending hordes of money on it. Take what you learn from CarSim and understand that it is not a perfect solution. Compliance, tires, and manufacturing will not be perfect and these will effect correlation.

You may have interesting results in either event if your coefficient of friction is between 2 and 3...