A brief browse of File::Find's documentation suggests that the preprocess option might do the trick

use strict;
use File::Find;

find({
    preprocess => \&preprocess,
    wanted     => \&wanted,
}, ".");

# munge data so wanted() gets the desired input
sub preprocess {
    my @files  = @_;
    ...
}

sub wanted {
    ...
}
[download]

HTH

broquaint