If you do not have a Hand Primer and you do not want to rig up some sort of primer Pump to fill up the Fuel Lines going up to the Fuel Injection Pump in theory you are left with Cranking the Engine with hope it does not ruin your Battery or Starter.

I suppose jacking up the Rear of the Car so the Tank is higher than the Fuel Injection Pump would help.

As You said loosening the Fuel Injection Line Nuts will help Bleed the Air out faster and may tell you if you are getting enough Fuel to attempt to start.

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84 300D, 82 Volvo 244Gl Diesel