In reply to SebCa:
> this would be ideal as the pain between climbs is well...pain...
Sorry if this is a very obvious question, but are you taking your new shoes off between climbs? Breaking in new shoes is going to be far less painful if you do it starting with little stints of five minutes at a time, rather than trying to wear brand new shoes continuously for a couple of hours.
Best method I know for heat-moulding new shoes is: double-bag shoes in plastic bags as hermetically sealed as you can manage, put in a nest of towels in a large pot, pour boiling water over the top, leave them until the rubber's warmed up and softened -- about 15 mins, IIRC -- then put them on and wear them as long as you can. That really does work to accelerate the breaking-in process.
But I'd try the obvious things first.
And if you're finding new shoes agonizing even for a few minutes, then I'd seriously consider if they're too small and/or a bad fit for your feet. Uncomfortable is one thing, excruciating is another!