const
  RemoteName = '\ntmemo01C$';
  UserName = 'yourusername';
  Password = 'yourpassword';

function MapNetworkDrive: Boolean;
var
  NetRes: TNetResource;
  Res: DWord;
begin
  Result := True;
  FillChar(NetRes, SizeOf(TNetResource), 0);
  NetRes.dwType := RESOURCETYPE_DISK;
  NetRes.lpRemoteName := PChar(RemoteName);
  NetRes.lpLocalName := 'H:';   // Whatever drive letter you want
  Res := WNetAddConnection2(NetRes, PChar(Password), PChar(UserName), 0);
  Result := (Res = NO_ERROR);
end;

function UnMapNetworkDrive: Boolean;
var
  Res: DWord;
begin
  Res := WNetCancelConnection2(PChar('H:'), 0, True); // same drive letter as above
  Result := (Res + NO_ERROR);
end;