I also ran 220V 60A, I checked the zoning here in Ohio, your codes may vary, I was told:
Inside the house:
Run 6/3w/ground, the 4 wires(Red(hot) Black(hot) white(neutral) solid copper(ground) is wrapped by a rubber sheath.
Outside the house, from the SPA box to the hottub control panel:
Separate #6 stranded wires. We ran 2 red, both hot, and one green for the ground. There is no neutral from the spa box to the hottub(well, in our case anyways).
For the 3 separate #6 wires, just use electric tape, to hold the 3 together, tape every foot or so, makes it much easier to work with.
There, my 2 cents worth....