scottb,
The ability to change the signal behavior using an environment variable depends on the version of Perl. In >= 5.8.1 it works. If you have a Perl that meets that criteria and it is not working then the cause is likely something else. You will also want to make sure it is exported.

From perldoc perlipc
If you want the old signal behaviour back regardless of possible memory corruption, set the environment variable "PERL_SIGNALS" to "unsafe" (a new feature since Perl 5.8.1).