You should take a look at perlcall, perlapi and perlguts.

But since I was working on something similar for PLJava and PLDelphi, here's some snippets with some extra comments:

char*
EmbedPerl_call_args( char* code , char* arg1 ) {
  // dTHX enables multiple Perl interpreters for the API functions:
  dTHX ;
  // Enables the call of sub from C (handles @_ and returned values):
  dSP ;

  char *tmp , *retval ;
  SV* ret ;
  
  // Enable the call of the function from multiple native threads:
  PERL_SET_CONTEXT(PL_curinterp) ;

  // enter and save tmp to enable call to perl function (handles @_ fo
+r us):
  ENTER ;
  SAVETMPS ;

    // Enable the insertion of arguments to send to the sub call:
    PUSHMARK(SP) ;
      // add arg1 as a new SV in the arguments (@_):
      XPUSHs(sv_2mortal(newSVpv(arg1, strlen(arg1))));
    PUTBACK ;
  
    // call the sub:
    call_pv(code , G_SCALAR);

    // refresh returneds to get returned value:
    SPAGAIN ;

    // get the SV returned (SCALAR context):
    ret = POPs ;
    
    // tmp will point to the internal char* of the SCALAR, so,
    // when we clean the scalar we clean tmp, and can't return it...
    tmp = SvPV(ret , len) ;
    // ... so, we copy tmp to retval to can return the char* after cle
+an tmps:
    retval = malloc(sizeof(char) * (len+1)) ;
    Copy(tmp, retval, len, char);
    // add end of char*:
    retval[len] = '\0';
  
  // clean tmps and return to the previous state:
  FREETMPS ;
  LEAVE ;

  // the returned value:
  return retval  ;
}
[download]

You also can take a look at the sources of LibZip, at ./myldr/ and ./myldr/zlib-src/main.c to see sources of an executable that do that and for a MakeFile.PL that compile automatically your app on Linux and Windows.

Enjoy!