I have taken care of these types of site specific problems
by using autoconf. I believe perl configure might be a good (or better) solution
But I am not that familiar with it. Here's a quick start on autoconf. Autoconf has a lot of documentation.

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ ls -l
total 2
-rwxrwxrwx    1 LameNerd     None          320 Jul  8 11:47 configure.
+ac
-rwxrwxrwx    1 LameNerd     None          231 Jul  8 11:48 test.in

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ cat configure.ac 
AC_INIT( test, 1.0 )


dnl 
AC_DEFUN([AC_ORACLE_HOME],[dnl

AC_MSG_CHECKING(Checking for oracle home)
if test -z "$ORACLE_HOME"; then
AC_ERROR(No oracle home env var)
else
AC_MSG_RESULT(ok)
AC_SUBST( ORACLE_HOME, "$ORACLE_HOME" )
fi
])dnl
dnl 


AC_ORACLE_HOME( ORACLE_HOME )


AC_OUTPUT( [ test] )

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ cat test.in 
#!/bin/sh
####################################################
### This script is intended as a example of how to 
### use autoconf to determine ORACLE_HOME.
####################################################
@ORACLE_HOME@

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ autoconf

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ ls -l
total 65
drwxr-xr-x+   2 LameNerd     None            0 Jul  8 11:48 autom4te.c
+ache
-rwxrwxrwx    1 LameNerd     None        64409 Jul  8 11:48 configure
-rwxrwxrwx    1 LameNerd     None          320 Jul  8 11:47 configure.
+ac
-rwxrwxrwx    1 LameNerd     None          231 Jul  8 11:48 test.in

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ ./configure
checking Checking for oracle home... ok
configure: creating ./config.status
config.status: creating test

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ ls -l
total 90
drwxr-xr-x+   2 LameNerd     None            0 Jul  8 11:48 autom4te.c
+ache
-rw-rw-rw-    1 LameNerd     None         3630 Jul  8 11:49 config.log
-rwxrwxrwx    1 LameNerd     None        19840 Jul  8 11:48 config.sta
+tus
-rwxrwxrwx    1 LameNerd     None        64409 Jul  8 11:48 configure
-rwxrwxrwx    1 LameNerd     None          320 Jul  8 11:47 configure.
+ac
-rw-rw-rw-    1 LameNerd     None          227 Jul  8 11:49 test
-rwxrwxrwx    1 LameNerd     None          231 Jul  8 11:48 test.in

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$ cat test
#!/bin/sh
####################################################
### This script is intended as a example of how to 
### use autoconf to determine ORACLE_HOME.
####################################################
d:\Oracle\Ora81

LameNerd@maxtrix6 ~/scripts_IN/conf_test
$
[download]