calling external previously registered functions from a DLL

[clonfsp]

I have a dll whitch init a thread in dllmain.
After than, the calling application call some dll functions which register the remote function of the application.
function register done, when the thread works and receives and even, it call the program functions (those I stored register before)

how can this be done?
int C would be like:

int (__stdcall *f_wmif) (char *) = NULL;

INT __declspec(dllexport) __stdcall _DGTDLL_RegisterWMIFunc (int (__stdcall *whitemoveinputfunc) (char *)) {
	f_wmif=whitemoveinputfunc;
	return OK;
}

.....
.....
f_wmif(x);
.....
.....

I dont know how can I do this in VB. Any help will be wellcame