Thanks herveus, this has worked a treat! I changed the 'and' to an 'or', and slightly changed the 'exec', but otherwise followed your example pretty closely. My new BEGIN block follows:

BEGIN
{
     if (!defined($ENV{'ORACLE_HOME'}) || !defined($ENV{'LD_LIBRARY_PA
+TH'}))
     {
         $ENV{'ORACLE_HOME'}     = "/users/oracle/product/9.2.0";
         $ENV{'LD_LIBRARY_PATH'} = $ENV{'ORACLE_HOME'} . "/lib";
         exec($^X, $0, @ARGV);
     }
}
[download]

Thanks again,
mildside