You can attach short bolt on forks and there are places that sell these, but why dont you just use your FEL?
To turn my compost (18-20 yard pile) I curl the bucket and drag backwards from the top of the pile spreading it out about 25' long then I use the FEL to scoop the left and right sides into the center and then scoop up the stuff I backdragged into the pile again.
The other aspect is turning or not. Cornell U and others say turnng is not really necessary once its well mixed so I turn mine 2 times in the fall after leaf collection and then 2-3 times in the summer before I spread it.
IF you are in continously adding to the pile make a longer pile and blend new material into one end then use material from the opposite end works too.