...
my @fields = split( / /, $config->get_fields );
my @vars = map {'$' . $_} @fields;
my $str_var = join(" ", @vars);

my $template = Text::Template->new(
    TYPE   => 'FILE',
    SOURCE => $tf,
    PREPEND => 'use strict;
            use vars eval($str_var);
        ',
   ) or die "Couldn't construct template: $Text::Template::ERROR";