If you have the official Honda T-handle tool you don't have the option of using an impact wrench.
You can fake it with a hammer though, tapping one arm of the tee. Once the nut breaks free it spins off easily. If you can get someone to hold the clutch with gloves while you do this it will be a lot easier. You may be able to wrap a hold-down strap around the centre spline and pass it through the basket fingers to tie off on something solid?
Anyway I've used the T wrench a lot and I don't remember any big trouble getting the nut free (or tight).