-bash: /usr/local/ese/bin/ese_configurator.pl: /usr/local/ese/bin/p
+erl: bad interpreter: No such file or directory
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Could you make sure that the interpreter does exist and works by running:

/usr/local/ese/bin/perl
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and also

ldd /usr/local/ese/perl/bin/perl5.8.6
        not a dynamic executable>
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what's the relation of the above to the aforementioned interpreter?

Using Perlbrew to install an older Perl version, while your system uses its own, is the way to go. But you need to be able to use it without interference from system-installed Perl.

Perl XS modules need recompilation when system libraries that they depend on change. I guess even legacy Perls need their XS modules recompiled when OS changes libraries.

How about creating a new user. In this user's bash script (login script etc.) you specify to use Perlbrew perl5.8.6 then as that user you should be able to run $ perl -v and get 5.8.6. then install all modules that NorthernLight requires manually (you need to list them somehow, but also running the executables and when they fail on ... XXX not found you install it and move on until it stops complaining, it can work) as this user you just created.

Edit: I mean, re-install perl5.8.6 with perlbrew manually. Do not depend on the NortherLight's Perl installation at all. Unless they made proprietary changes to the code, compiled it and now are providing binaries to you. Which obviously has a sell-by date ...