I've used a C-clamp, with the non-turning head of the c-clamp against the threaded end of the pin, with the nut set right at the end so the clamp bears on the nut and the end of the pin both. On the turning side of the c-clamp, I put a socket that was just big enough to fit over the head of the taper pin, and the turning side of the c-clamp bearing on the square drive side of the socket.
Saturate with penetrating oil, put some pre-load on it with the c-clamp, and tap the side of the gear leg sleeve with a hammer.
It goes without saying that the airplane is jacked up so there's no weight on the gear leg, right?