You could do it like this, but I doubt the error messages
from deep inside boost::function will be very helpful.

template<class BoostF, class F>

class CheckFunctionCompatible {
public:
  BOOST_CONCEPT_USAGE(CheckFunctionCompatible) {
      BoostF test(f);
  }
private:
  F f;
};

In Christ,
Steven Watanabe