You could simply get one of those 2.5 liter spare Fuel Containers and run your Fuel inlet hose into that; and see if you can get the hand primer to get that Fuel into the Fuel Injection Pump.
If you can get the Car running like that drive it to someplace where there is a heated Garage so that the whole Car Can be warmed up and try your Fuel Additive.

For entertainment purposes I came up with an emergency plan.
I remember seeing a documentary about Alaska. It several degrees below zero out side but inside of an Igloo with a small Fire going it was 27 Degrees F.

This makes me think that you could make Snow Wall of packed Snow just under the perimeter of your Car to more or less seal off from the outside weather.

Where it is safe under the Car put several short but long burning lit Candles; above the Candles it must be safe from the Candle flames. And, see if that would heat it up enough to de-gel the fuel.

You could also do a similar thing as above but instead of candles use another heat source like the Exhaust of a Gas Car piped under the car. But, remember you need to have the all the Windows down on the Diesel Car to avoid being poisoned.
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84 300D, 82 Volvo 244Gl Diesel