#!/usr/bin/perl -w
use strict;

my $string = '111111111:22222\:2222:333333333:4444444';

$string =~ s/\\:/:/;     #translate \: to just :
                         #the "trick" and its all over now...
                         
chomp ($string);         #don't worry about trailing \n

my @strings = split (/:/,$string);

foreach my $line (@strings)
{
   print "$line\n";
}
__END__
prints:
111111111
22222
2222
333333333
4444444