BTW: The method used here fails in the following cases:

c:\@Work\Perl\monks>perl -wMstrict -le
"for my $word (qw(XYZ$-.%abc&/  $-.%abc&/XYZ  $-.%abc&/XYZ+=*)) {
   my @group1 = ( $word =~
     m/(?:
       ([^a-zA-Z]+)
       ([a-zA-Z]+)
      )+
      ([^a-zA-Z]+)
     /x );
   my @group2 =
     map { $_ =~ /[a-zA-Z]/ ? split( //, $_ ) : $_ } @group1;
   my $new_word = join ( '', map { qq{[$_]} } @group2 );
   print qq{'$word' -> '$new_word'};
   }
"
'XYZ$-.%abc&/' -> '[$-.%][a][b][c][&/]'
'$-.%abc&/XYZ' -> '[$-.%][a][b][c][&/]'
'$-.%abc&/XYZ+=*' -> '[&/][X][Y][Z][+=*]'
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(Again, this assumes that we can, to begin with, even arrive at a common understanding of what is required. :)