dsPIC33E External Interrupts INT0,INT1,INT2 not firing
At this point I feel fairly certain the problem was the line

 INTCON2 = 0x0000;


which effectively disabled bit 15 (global interrupt enable). The following is a working initialization function. 

void BldcHallSensorInit( void )
{
// Hall Sensor A                | Pin 31    RPI24       RA8     INT2
// Hall Sensor B                | Pin 35    RPI51       RC3     INT1
// Hall Sensor C                | Pin 46    RP39        RB7     not mappable


TRISAbits.TRISA8 = 1 ;
TRISCbits.TRISC3 = 1 ;

RPINR0bits.INT1R = 51;  //001 1000;     // Set Hall B = RPI51/RC3 set INT2
RPINR1bits.INT2R = 24;  //011 0011      // Set Hall A - RPI24/RA8 set INT1 


//CORCONbits.IPL3 = 0;
//INTCON1bits.NSTDIS = 0; // interrupt nesting enabled.
//INTCON2bits.DISI = 0 ;
//INTCON2bits.SWTRAP = 0 ;

//INTCON2 = 0x0000;       // **erroneous line**       

// Reset Interrupt flags.
IFS0bits.INT0IF = 0;      //Reset INT1 interrupt flag 
IFS1bits.INT1IF = 0;    //Reset INT0 interrupt flag
IFS1bits.INT2IF = 0;    //Reset INT0 interrupt flag

// Interrupt edge polarity.
INTCON2bits.INT0EP = 1 ;
INTCON2bits.INT1EP = 1 ;
INTCON2bits.INT2EP = 1 ;

// Set Interrupt Priority.
IPC0bits.INT0IP = 1;    // set low priority.
IPC5bits.INT1IP = 1;    // set low priority.
IPC7bits.INT2IP = 1;    // set low priority.

// Enable Interrupts.
IEC0bits.INT0IE = 1;    // Enable INT0 Interrupt Service Routine.
IEC1bits.INT1IE = 1;    // Enable INT1 Interrupt Service Routine. 
IEC1bits.INT2IE = 1;    // Enable INT2 Interrupt Service Routine.

INTCON2bits.GIE = 1;    // Global Interrupt Enable. Order/placement of this
                        // line is important.
}