split and join to the rescue: 

my $string = "huckabee AND jfkadlsfj  fdsfldfj06329 OR reagan AND bide
+n AND clinton OR sebelius OR mccain";

my @chunks = split / AND /, $string;
@chunks = map { /OR/ ? "($_)" : $_ } @chunks;
print join(' AND ', @chunks), "\n";
__END__
huckabee AND (jfkadlsfj  fdsfldfj06329 OR reagan) AND biden AND (clint
+on OR sebelius OR mccain)

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In reply to Re: Building a boolean search engine by moritz
in thread Building a boolean search engine by Anonymous Monk

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