Is underhand considered a route now?
I know the sextension feels like it but...I digress...
That description makes little sense to me Robl - I'm guessing you mean the move out to the juggy pocket (and hence end of hard climbing)? If so - left foot is on edge furthest left and pretty high under the roof, right heel is hugging the right lip of the roof, left hand sloping pocket under roof, right hand good slot above roof, then.... Slap left hand, feet come off, hold swing, romp.
If you do mean that move then you've already done the hardest bit (getting right hand slot above roof) - Good luck on it, a classic on the Cliff circuit.