[ODE] nearcallback pointer help

[Christopher Harvey]

Hello,
I've created a Physics class, here is the .h file.

---------------------------------------------------------------------------------------------------------------
/*
This class holds all the data for all the objects that have to be synchronized 
on each client.
It also handles the simulation calculations.
*/

#ifndef PHYSICS_MANAGER
#define PHYSICS_MANAGER

#include "Globals.h"

#define MAX_CONTACTS	100		//Really not sure at all what this should be
								//TODO: test to see if we can find out how many it is actually using.
//#include <windows.h>
#include <GL/gl.h>
#include <ode/ode.h>
#include <vector>
#include "timer.h"
using namespace std;

class PhysicsManager
{
public:
	PhysicsManager();
	~PhysicsManager();

	void SetState(const char *fileName);
	void SaveState(const char *fileName);
	dBodyID AddBox(float *sides, float density, float *position);
	bool RemoveBody(dBodyID id);

	void PhysicsStep(double dt);
	void RenderGeoms();
private:
	void ODEtoOGL(float * M, const float *p, const float *R);
	void DrawBox(const float sides[3], const float R[12]);
	unsigned int getFreeID();
	vector<dBodyID> physicsBodies;

	dWorldID World;
	dSpaceID Space;
	dJointGroupID contactgroup;

//	void nearCallback (void *data, dGeomID o1, dGeomID o2);
};

#endif
----------------------------------------------------------------------------------

Here is my question:
I want to pass the nearcallback function into the dSpaceCollide();
However, I can't cast it into a pointer because it's not a static member. If I 
make it a static member it can't access the World and Space variables, 
because they are not static either. 
I don't mind changing the whole implementation, if there is a known way to 
encapsulate ode in a class. Any ideas?
Thanks in advance.