The good news is, I think it should work in the future when constexpr is more widely available.  On compilers that aren't there yet, you need to use something with a static constant instead.

Try:

#include <boost/gil/gil_all.hpp>
#include <boost/integer_traits.hpp>

using namespace std;
using namespace boost;

int main()
{
  typedef mpl::integral_c< unsigned char
                         , integer_traits< unsigned char >::const_max
                         > my_max_value_t;


          return 0;
}