You can also complicate it to avoid the loop (in fact, disguise it as a repetition) and the // operator:

push @{ $h{$_} }, shift @B for (@A, reverse @A) x (@B / @A / 2),
                               (@A, reverse @A)[ 0 .. @B % (2 * @A) - 
+1 ];
[download]

Update: Another idea:

for my $i (0 .. $#A) {
    $h{ $A[$i] } = [ @B[ grep { my $m = $_ % (2 * @A);
                                grep $_ == $m, $i, 2 * @A - $i - 1
                              } 0 .. $#B ] ];
}
[download]

TIMTOWTDI, an iterator:

my $iter = do {
    my ($pos, $step) = ('0E0', 1);
    sub {
        my $r = $H{ $A[$pos] } ||= [];
        if ($pos % $#A || $pos =~ /E/) {
            $pos += $step;
        } else {
            $pos .= 'E0';
            $step *= -1;
        }
        return $r
    }
};
push @{ $iter->() }, $_ for @B;
[download]