OMAP-L138: how to hook an interrupt without TI/RTOS

I'm currently using processor_sdk_rtos_omapl138_5_01_00_11 on the DSP side of an OMAP L138 and have this code:

void dspEdma3EnableInterrupts(void) {
  *INTMUX3 = (*INTMUX3 & 0xFFFFFF00) | EDMA3_0_CC0_INT1; // maps INT12 to EDMA_0_CC0_INT1
  edma3_hwi_handle = Hwi_create(12, dspEdma3Isr, NULL, NULL);
  WHICH_EDMA3[IESR] = (1 << PARAM_SLOT_START); // NB, per sprugp9b pg 112, we cannot write IER directly!
  Hwi_enableInterrupt(12);
}

void dspEdma3Disable(void) { // call AFTER dspMcaspDisable()!
  Edma3Param *start = (Edma3Param *) &(WHICH_EDMA3[PARAM(PARAM_SLOT_START)]);
  memset(start, 0, sizeof(Edma3Param));
  WHICH_EDMA3[EECR] = (1 << PARAM_SLOT_START); // NB, sprugp9b, pg 110, cannot write EER directly;
  Hwi_delete(&edma3_hwi_handle);
  Hwi_disableInterrupt(12);
}

I'm trying to shed the RTOS.  I need to replace all the Hwi_* functions.

What is the equivalent bare metal way to do this?

I suspect what I need to know is (a) where in memory the interrupt vector table is and (b) how to enable/disable the interrupt.

I found the CSR.GIE and IER, so that's good.  Can I write them directly? I'm assuming yes.

I found the ISTP, but it points at 0x00700000, which is the L2ROM, so I suspect I need to move it in to RAM.

How do I write to the ISTP from C?

It looks like i need 0x20 bytes * 16 entries == 0x200 bytes.  But what goes here?  It should be executable instructions?  Does it need to be aligned in any way?  I'm assuming yes, and 4 bytes.

Looking at the existing entries, they all seem different, so I'm not sure what a generic entry would look like.  Maybe sprufe8b.pdf or sprui04b.pdf can help me...

I'm not a DSP assembly guru, so I'm a little lost at this point...