This might help but its for timer1 on a AT89S8253 ... you only need change the corresponding interrupt vector name.
Just a cut and paste from MikroC samples folder.
//-------------- Interrupt handler routine
void Timer1InterruptHandler() org IVT_ADDR_ET1{
EA_bit = 0; // Clear global interrupt enable flag
TR1_bit = 0; // Stop Timer1
TH1 = 0x00; // Reset Timer1 high byte
TL1 = 0x00; // Reset Timer1 low byte
P0 = ~P0; // Toggle PORT0
EA_bit = 1; // Set global interrupt enable flag
TR1_bit = 1; // Run Timer1
}
void main() {
P0 = 0; // Initialize PORT0
TF1_bit = 0; // Ensure that Timer1 interrupt flag is cleared
ET1_bit = 1; // Enable Timer1 interrupt
EA_bit = 1; // Set global interrupt enable
GATE1_bit = 0; // Clear this flag to enable Timer1 whenever TR1 bit is set.
C_T1_bit = 0; // Set Timer operation: Timer1 counts the divided-down systam clock.
M11_bit = 0; // M11_M01 = 01 => Mode 1(16-bit Timer/Counter)
M01_bit = 1;
TR1_bit = 0; // Turn off Timer1
TH1 = 0x00; // Set Timer1 high byte
TL1 = 0x00; // Set Timer1 low byte
TR1_bit = 1; // Run Timer1
}