Might I suggest that to make this cut on a tablesaw, you would
need to add an attachment to your fence to make it as high as perhaps
20 inches. Then tilt your saw blade 30 degrees and run the piece
to be cut through the saw in an upright or vertical position. End
result should be a 60 degree bevel. Be careful to keep the piece
as tight to the fence as possible when running it through.
Something like a "featherboard" will help in this regard. Good
luck.
Garth