Is there a way to install the modules it uses "on demand"?

Here's what I've done in one script:

 202     my @variables =
           qw/User Password Url Prefix CommPlan ApiVersion/;
 203     foreach my $site ( grep { $_->{'enabled'} == 1 }
           @{$json_config} ) {
 204 
 205       use lib '/some/path';
 206       eval "use FOO::$site->{'module'}";
 207 
 208       my %variables =
 209         map { $_ => eval '$' .
               join( '::', 'FOO', $site->{'module'}, $_ ) }
 210         @variables;
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This pulls in variables for each individual website, where the website credentials are stored in modules -- which are not stored in version control, obviously. I could also have put them in json files, but I liked the idea of using a module so that I could add dated comments to remember related information.