There is a simple yet effective way of using redirection, without the need for a module.

Use it just as you'd do an http header.

# code to resolve what $url is going to be
# ...

# redirection
print "Location: $url\n\n";
[download]

'Location' is a standard CGI header, just like 'Content-type' and you'd use them the same way: make it the first thing your CGI script prints out, and make 2 newlines afterwards.

This code is tested and works (providing you fill in the blanks). I used it for an anti-leech download page found here.