You could use lvalue refs:

#! perl -slw
use strict;

my $data = <<EOD;
record 1
record 2 is a bit longer
record 3 is just this length
EOD

my $p = 0;
my @refs;

while( my $o = 1+index $data, "\n", $p ) {
    push @refs, \substr $data, $p, $o - $p;
    $p = $o
}

print $$_ for @refs;
[download]

which works okay (from 5.8.4 (maybe 5.8.3 I forget) onwards), but don't try assigning to them unless your replacements are exactly the same length as the originals.