you probably really do want to look into an event system that will prescribe a bit of pre-built organization but if you just want to store the bind for later boost function will do it.

http://www.boost.org/doc/libs/1_46_1/doc/html/function.html

#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <iostream>

boost::function<void (std::string)> func;

class Object {
    void runner(std::string message) {
        std::cout << message << std::endl;
    }

public:
    void assign() {
        func = boost::bind(&Object::runner, this, _1);
    }
};

int main(int argc, char **argv) {
    Object obj;
    obj.assign();
    func("my message");
    return 0;
}