Replacing the seals in the air-can isn't going to be the hard part. The hard part is going to be getting the air-can off. Your shock has the old style threaded on lower body eyelet and this will need removed (after the shock is depressurised) to get the air-can off.
I would suggest looking for a more modern shock in a 6.25/1.25" length (even 6.5/1.5 works well on those FSR MAX frames) and put this shock in the antiquities collection.
It's good to see someone with a well looked after and still ridden FSR Max.