How about this heavy-handed approach. An automatic login script that sets up the perl environment for the users. Save it as /etc/perl_config.pl.

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

# Validate current user
die "Unknown user!" if (!$ENV{LOGIN});

# Load user configuration (from external file or from this script)
my %config;
while (<DATA>)
{
    chomp;
    my ($user, $pref) = /(\w+)\s+(.*)\/perl/;
    $config{$user} = $pref;
}

# Find out the preferred perl version for this user
# If user not seen in the config file, set to default
# path to the latest version of perl
my $path = $config{$ENV{LOGIN}} || "/usr/local/bin";

# Export the modified path for the user
print "export PATH=$path:\${PATH}\n";

__DATA__
roger   /usr/bin/perl
james   /usr/local/bin/perl
thomas  /usr/bin/perl
peter   /usr/perl/bin/perl
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Note the format of the config file, to make it a bit easier to maintain and understand, I have chosen to put the full path to perl executable against each user (rather than path to bin directory), and the script will strip out the /perl bit before printing the modified path to STDOUT.

In user's login shell, just add the following:

eval $(/etc/perl_config.pl)
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To the system /etc/profile or user's ~/.bash_profile.