Before anyone rips me for not using CGI, I want to let it be known that I am unable to use CGI for this application due to the server I will be using it on.
I don't buy that one. Sorry.
If it's a recent usable version of Perl, then CGI.pm came with it.
Even if it's not, CGI.pm is a single file. Download it, extract it from the distribution,
and place it in the "current directory", likely the same place as your script,
or add a use lib... directive to point to its location.
Even if that option is not available, because they've said "your application must fit in a single file" (a ludicrous requirement, but work with me on this one),
you can edit your single file as follows:
... insert contents of CGI.pm here, stopping just before the __END__ t
... your code goes here ...
my $foo = param("bar");
... more of your code goes here ...
There. No excuses. Use CGI.pm.
-- Randal L. Schwartz, Perl hacker