sub SetLog {
  my $glob = shift;
  *LogFile = *$glob;
}

##</code><code>##

package test_a;
my $LOGFH;
sub SetLog {
  $LOGFH = shift;
}
sub TestLog {
  print $LOGFH "test_a::TestLog...\n";
}

package main;
...
test_a::SetLog(\*LOGF);