One option is to use a regex to match just two chars at a time--globally--and place the results into an array:

use strict;
use warnings;

my $string = '8602353907455755';
my @arr = $string =~ /../g;

print "@arr";
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Output:

Hope this helps!

An example using unpack:

c:\@Work\Perl\monks>perl -wMstrict -le
"my $string = '8602353907455755';
 my @arr = unpack '(a2)*', $string;
 print qq{@arr};
"
86 02 35 39 07 45 57 55
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Sure looks to me that the h (or H) formats are just what the doctor ordered.   (FYI:   the format-strings are defined, in very great detail, in perldoc pack.)

See also perlpacktut.

---

Give a man a fish:  <%-{-{-{-<

It's unclear to me if mike65535 wants to unpack the example string given in the OP as pairs of characters to yield an array
    ('86', '02', '35', '39', ...)
or, interpreting each character pair as a hex byte, to produce
    (0x86, 0x02, 0x35, 0x39, ...)
or maybe something else. Can the OPer please clarify?

Update: Oh, what the heck... Here's an example of the latter to go with the example of the former given above:

c:\@Work\Perl\monks>perl -wMstrict -MData::Dumper -le
"my $string = '8602353907455755';
 my @arr = unpack 'C*', pack 'H*', $string;
 print Dumper \@arr;
"
$VAR1 = [
          134,
          2,
          53,
          57,
          7,
          69,
          87,
          85
        ];
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Thanks for all the snippets!

To the request that I "clarify" - I realize it's bad form but I'm not sure in what form I want the data.

My first guess is any of the techniques will generate useful output for me, but I'm sure one will work better. ;-)

Thanks again.