The answer is probably NO.
Let me explain, after I have setup a new server (including installing the login script) I would reboot before I connect any windows machine to the server. I have never added the required rpm to an SME that was currently being used, so that is why the answer is "probably"
If I have to change a login script or change a user’s access then the answer is NO, just make the changes in SME and then save. The windows user will have to log off and back on for the changes to take effect.
With your current server do windows users login to the domain? If they do I would think that you could just install the rpm, create your script, and then save in SME, then have your users log off and back on.
Good luck