gistfile1.c

#include  <msp430x20x3.h>

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer
  
  P1DIR |= BIT6;                            // Set P1.6 to output direction
  P1SEL |= BIT6;							// P1.6 to TA0.1
  
  CCR0 = 1000-1;             				// PWM Period
  CCTL1 = OUTMOD_7;          				// CCR1 reset/set
  CCR1 = 0;                					// CCR1 PWM duty cycle
  TACTL = TASSEL_2 + MC_1;   				// SMCLK, up mode
 
  P1IE |= BIT3;                             // P1.3 interrupt enabled
  P1IES |= BIT3;                            // P1.3 Hi/lo edge
  P1IFG &= ~BIT3;                           // P1.3 IFG cleared

  _BIS_SR(LPM0_bits + LPM4_bits + GIE);     // Enter LPM4 w/interrupt
}

// Port 1 interrupt service routine
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void)
{
  P1IFG &= ~BIT3;                           // P1.3 IFG cleared
  CCR1 = (CCR1 + 250) % 1000;				// Add 25% to PWM
}

Thanks Adam. This has really helped me!