Why not just encode the other characters manually? 
use HTML::Entities ;

my $string = '[< smarto  >]';

my $unsafe_chars = '[]';
my $encoded = encode_entities($string)
                =~ s{([\Q$unsafe_chars\E])}{sprintf"&#%d;",ord$1}egr;

print "$string\n$encoded\n";

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In reply to Re^3: HTML::Entities encode_entities for perlmonks [ ] by trizen
in thread HTML::Entities encode_entities for perlmonks [ ] by Anonymous Monk

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