I basically keep doing the same kinds of training that I do during the rest of the year, except board climbing, because the holds are just painfully hot.
At the moment I fingerboard more often.
I reckon that training power or HIIT is a nightmare of sweat, fatigue and fire breathing.
I'd say that doing long laps of ARC on jugs with taped fingers could do the trick, if you fancy such an abomination.
Should you need more info, you can check my Power Club entries of the last 8/10 weeks. It was 39,5 degrees today in Florence, by the way. 'nuff said.