I don't know if your magic elixir will work since I don't know anything about your pump. Maybe yes, and maybe no.
One thing is for certain: a new seal kit and the special tool you'd need to do that job is less than than the magic fluid. If the main shaft seal is the one that is leaking, then magic fluid won't do it. And if it is the usual culprits leaking, then you are better off with new seals anyway.
But, have a go, and let us know how it is doing. Also, check to see if the hose leading to the coolant recovery tank is OK or if leaking diesel has degraded that hose. It is the smaller one coming off a metal stub below the distribution line end of the injection pump.
Cheers,
PH