Simulating IBIS Model in modelSim
I don't think you can use Ibis in Modelsim... For Ibis, you need a signal integrity simulator such as Hyperlynx. But its purpose is to ensure the integrity of high speed signals, including the effects of PCB traces on waveforms.

If you are modelling the digital interactions between your FPGA and the TI chip, you need a "bus functional model" for that chip in your HDL of choice. Contact your TI FAE for this. 

If TI can't supply one, you will have to write your own, using the datasheet timing diagrams to model the bus transactions.