Simulating a TI microcontroller in Spice
Proteus should be able to simulate an MSP430. See this page for simulating the MSP430 series.

However, keep in mind that relying on a simulator to accurately simulate MCU behaviour may result in trouble. Also, Proteus is not free.

In many cases, you will be much better off leaving the MCU out of the equation, and simulating only the analog or digital portion of your circuit.

Also, I'm not familiar with it, but VisSim may also be an option.