Well, if there is a perl-ish way to do it, I just don't know how to do it. Here is the simple loop over array while storing the start and end of each char way:

@array=qw(x x y z z z);

$c=$array[0];
$start=0;
$end=0;

for $index (1..$#array){
if (!($c eq $array[$index])){
push(@output, $start, $end);
$c=$array[$index];
$start=$index;
$end=$index;
}else{
$end=$index;
}
}
push(@output, $start, $end);

print join(" ", @output), "\n";

Outputs:
0 1 2 2 3 5
[download]

I'm sure there someone else can probably do better.

Cheers