Math::Random::MT's rand is actually a Perl function.

srand is an XS function, so it expects to be called from Perl.

You'll need to use one of the methods in perlcall in both cases.

If you wanted to bypass Perl, you'd have to convert MT.pm and MT.xs to C, then compile and link MT.c, the converted code and your version of List/Util.c together.