First of all, only test this stuff on spare, unimportant partitions. I warned you!!!

Perl's not really suited to low-level stuff, except maybe for the regexing of the binary data you pump out. I know an old trick to read a bios is to use dd (on linux)

dd if=/dev/mem bs=32k skip=31 count=1 | strings -n 10 | grep -i bios
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You probably can use this same technique on raw disks, like

dd   if=/dev/hdb0  | strings -n 10 | grep -i  secretkey
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To put it in Perl, you probably can run it thru a piped open, and regex the output

my $pid = open(FH, " dd if=/dev/hdb0 | ") or die "$!\n";

while(  my $rrv = sysread( FH, my $buf, 1012 ) ){
         #regex your $buf here for whatever
         #of course you will have to worry about missing full strings
         #on your chunk boundaries, so you may need to save a few 
         #hunderd bytes of each $buf to add to the next one
      }
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