did any one already ported the free Rtos to this uC? is there any guideline ? thanks

I think the 149 is the same as the 449 but without the LCD controller?  If this is the case then there is a 449/IAR demo in the download already – look in the FreeRTOS/Demo/msp430_IAR directory directory.  There is not yet a documentation page for this demo but the demo is exactly the same as the other 449 demos so you can take a look at the documentation pages for those. Regards.