Help!!

I am trying to give users the ability to manipulate a file via a script that was written but I don't want the users (group of Sterling) to have write permission (for fear that it'll get deleted by accident) when using regular shell commands. I'm thinking that this is accomplished via Sticky bits. I've searched the man pages along with my Unix in a nutshell book and can't really find what I'm looking for. I'm not sure if I put the sticky bit at the file, script or directory level or all of the above. Can you guys take a look and see what I'm doing wrong?

Additionally, I am on AIX 4.3 (if that makes a difference)

The file I am wanting to protect Except when they run the script:

-rw-r--r-- 1 cdunix sterling 34918 Apr 08 09:49 univfile

The permissions on that directory are:
drwxrws--- 2 cdunix sterling 512 Apr 08 10:18 flatfile


Current permissions of the script that the user would be running:

-rwSrwsrw- 1 cdunix sterling 9174 Apr 08 09:47 addchgdel.sh

The permissions on that directory are:
drwxr-sr-x 5 cdunix sterling 1536 Apr 08 10:07 utils


Thanks in advance for taking a look!