To expand on Joost's suggestion, you could create a file containing the pre-specified NAME=VALUE pairs.

__DATA__

foo_field=foo's_value
bar_field=bar's_value
...
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Then, it's just a matter of getting a filehandle and instantiating a CGI object with it:

open(IFH, $CGI_filename) || die ...
my $query = CGI->new(IFH);

my $field = $query->param('foo_field');
print $field, "\n";

__OUTPUT__

foo's_value
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