The clean way to execute perl code setuid is to compile a wrapper from six lines of C code. See Security Bugs in perlsec.

Update:

This is the code from perlsec:

#define REAL_PATH "/path/to/script"
main(ac, av)
    char **av;
{
    execv(REAL_PATH, av);
}
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It is K&R style, quick and dirty, but it works.

If you prefer modern code that compiles cleanly even with gcc -Wall -pedantic, and that reports an error when executing the script fails, try this:

#include <unistd.h> /* for execv() */
#include <stdio.h> /* for perror() */

#define REAL_PATH "/path/to/script"

int main(int argc, char ** argv)
{
    execv(REAL_PATH, argv);
    perror("Can't execute main script");
    return 126;
}
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Note that the wrapper is setuid, not the script. The script inherits the setuid from the wrapper.

Alexander