Drain the oil and remove the oil strainer cover and strainer itself, then try introducing a magnet on a telescopic rod, (available from tool shops and hardware shops etc) and see if you can retrieve the pushrod that way, (the pushrod is ferrous but the crankcase is not). Failing that, jacking up one side of the vehicle or the other may just make it roll to a position where you can grab hold of it through the opening in the crankcase. If all else fails you will need to remove the engine and split the crankcase as there is no conventional sump pan you can remove. Good luck!
Lee
May 2008