You may find PerlPackTut a somewhat better introduction to pack & unpack than the bare perlfunc pod.

As a starting place for your application, this might help. This packs five bytes, hex values 0x40 - 0x44 into a string, prefixes it with a 32-bit little-endian byte count and then unpacks the whole thing and prints the length followed by the byte values interspered with '|'s.

print join'|', unpack 'V C*', pack 'V/A*', pack 'C*', 0x40, 0x41, 0x42
+, 0x43, 0x44;
5|64|65|66|67|68
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