If you can, use CGI.pm instead. cgi_lib.pl isn't too friendly when it comes to limiting that value (you'd have to hack it yourself).
CGI.pm also gives you many more benefits and functions that you can use, not to mention being more overly secure than any predecessor. I'm sure
merlyn or
tilly would be happy to argue about it more with you. (I'm sure hairs are growing out of their foreheads because of this debate.)