We can return this discussion to the perl domain by asking what a perl script can do if it finds itself with restricted, but modifiable, resource limits. The short answer is BSD::Resource from Jarkko Hietaniemi. It's a nice interface to the getrlimit and setrlimit calls (and a few others that cannot be invoked as perl builtins).
Resource limitations have to be addressed as subroutine calls, not by something invocable with system(). A child process can (try to) modify its own limits, but it cannot modify the limits of its parent.