In the Osprey book; German Defences in Italy in WWII on page 40, it states that a mobile crane was normally used, but it then states; "However, just as was the case with the tractors, as German's situation deteriorated heavy lifting gear was increasingly difficult to find. Instead the workers had to manoeuvre the individual sections along 'rail tracts' to their final resting place. It was then necessary to dig an incline down which the boxes were lowered. Once in place the concrete could be poured and the soil back filled."
Still, it does not mention how the turret was installed. It is possible that they used some sort of davit such as this;
Like the Pz 38(t) turret above, I am assuming the turret was mounted to a steel base plate, such that the traverse gears and bearing race were already installed, so that they would not be damaged during installation and the crew could manhandle it rather roughly without worrying about these rather delicate mechanisms. Nice color reference for Dunkelgelb there BTW.
Jentz and Doyle's Panzer Tracts produce a book on Pantherturms, including the wooden based ones. Panzer Tracts No. 21-2 - Pantherturm I und II (Panther Turrets on Steel, Concrete and Wood Stands.
Here is a diagram of one;