>>90,97

$ perldoc CGI | tail -n +767 | head -n 13
           The temporary directory is selected using the following algorithm:

               1. if the current user (e.g. "nobody") has a directory named
               "tmp" in its home directory, use that (Unix systems only).

               2. if the environment variable TMPDIR exists, use the location
               indicated.

               3. Otherwise try the locations /usr/tmp, /var/tmp, C:\temp,
               /tmp, /temp, ::Temporary Items, and \WWW_ROOT.

           Each of these locations is checked that it is a directory and is
           writable.  If not, the algorithm tries the next choice.
$

so it should be as easy as making a directory that's writable by the script and then setting the TMPDIR environment variable.