Hi Chmrr, you seem to have the answers to all of my problems today! Here's the relevant sections of the httpd.conf file:-

LoadModule perl_module modules/mod_perl.so

PerlOptions +SetupEnv +ParseHeaders +Parent -GlobalRequest
PerlSwitches -w -T
PerlRequire  "/var/www/startup.pl"

Alias /test  /var/www/test

<Directory /var/www/test>
    Options +ExecCGI
    Order allow,deny
    Allow from all
</Directory>

<Location /test/*.pl>
    SetHandler perl-script
    PerlResponseHandler ModPerl::Registry
</Location>

I've tried this with +Parent and -Parent (I'm trying to support multiple vhosts on this server), and also with +SetupEnv and -SetupEnv.