How to initialize Pwork in TLC file?

I am trying to use pwork vector as a way to store a pointer to a dll that I am loading. However, I also have a tlc file which I need to ( I think) incorporate this pwork vector somehow. I couldn't find much documentation for how to use pwork in tlc code, and would really appreciate if someone could help out. I've tried what I have below and it doesn't compile.

Here is the tlc code excerpt (the Pword stuff is probably wrong):

%%Function: Start ========================================================
%function Start(block, system) Output
    /* S-Function "WritetoVibrotactor_wrapper" Block: %<Name> */

    %assign pxd = LibBlockDWorkAddr(DSTATE, "", "", 0)
    %assign pwd = LibBlockPWork(PWORK, "", "", 0)
    WritetoVibrotactor_Start_wrapper(%<pxd>,%<pwd>);
    %%
  %endfunction

This is my s function code:

#define MDL_START
void mdlStart(SimStruct *S){
    real_T *xD = ssGetDiscStates(S);
    void *dllptr = LoadLibrary("TactorInterface.dll");
    ssSetPWorkValue(S,0,dllptr);
    WritetoVibrotactor_Start_wrapper(xD,dllptr);
}

Here is the wrapper code:

void WritetoVibrotactor_Start_wrapper(real_T *xD, void *hGetProcIDDLL)
{
 // void * hGetProcIDDLL = LoadLibrary("TactorInterface.dll");
 InitializeFn _InitializeTI = (InitializeFn)GetProcAddress(hGetProcIDDLL,"InitializeTI");
 ConnectFn _Connect = (ConnectFn)GetProcAddress(hGetProcIDDLL, "Connect");
 DiscoverFn _Discover = (DiscoverFn)GetProcAddress(hGetProcIDDLL, "Discover");
 ChangeGainFn _ChangeGain = (ChangeGainFn)GetProcAddress(hGetProcIDDLL, "ChangeGain");
 ChangeFreqFn _ChangeFreq = (ChangeFreqFn)GetProcAddress(hGetProcIDDLL, "ChangeFreq");
 PulseFn _Pulse = (PulseFn)GetProcAddress(hGetProcIDDLL, "Pulse");
 GetDiscoveredDeviceNameFn _GetDiscoveredDeviceName = (GetDiscoveredDeviceNameFn)GetProcAddress(hGetProcIDDLL, "GetDiscoveredDeviceName");
 CloseFn _Close = (CloseFn)GetProcAddress(hGetProcIDDLL, "Close");
 ShutdownFn _ShutdownTI = (ShutdownFn)GetProcAddress(hGetProcIDDLL, "ShutdownTI");

       int initret = _InitializeTI();
       int numdev = _Discover(3);
      const char *dev = _GetDiscoveredDeviceName(0);
      void *ptr = NULL;
     xD[1] = _Connect(dev,1,ptr);
       _ChangeFreq(0,1,1500,0);
       _ChangeGain(0,1,100,0);
       _Pulse(0,1,1000,0);
       FreeLibrary(hGetProcIDDLL);
  }