I put petrol in my 520d full tank aswell, I pulled the fuel hose in the engine bay and put an old rs turbo pump on it and dragged it out that way, I also syphoned the tank by pushing a hose down and using a wet vac to get enough suck to start it off,

All in worked well for me but your way round I would just try and tank it with petrol and it should be ok I would of thought