I'm not sure if you can make it more simple than the following:

package Foo;
use base qw(Net::Server::Fork);

my @ports = qw(20203 20204 20205);
my @dbs   = qw(tom   jim   jane);
my %p_map; @p_map{@ports} = @dbs;

Foo->run(port => \@ports);

sub process_request {
    my $self = shift;
    my $port = $self->get_property('sockport');
    my $db   = $p_map{$port};

    print "Welcome!  You connected on port $port - your db is $db\n";

    # run default echo server
    $self->SUPER::process_request(@_);
}
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If you are really opposed to Net::Server you could always read through its guts to see what it is doing and roll your own. Or keep your life simple. Enjoy!

Update: I guess really though this example is cheating - I haven't started three servers. I've only started one server that is listening on three ports. But I think it would be much much easier to maintain.

Update 2: Looking at your code you want a PreFork server. Well then you'd need to do the following:

use base qw(Net::Server::PreForkSimple);

Foo->run(
  max_servers  => 5, # from jwlewis sample code
  max_requests => 5,
  port         => \@ports,
);
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