Try this link...this web part worked for me (It allows administrator to set
alerts for other users):

weblogs.asp.net/jan/archive/2004/03/27/97335.aspx

Take a look at
https://shop.sharepointsolutions.com/p-12-wss-alert-manager-1000.aspx

Yes, WSS Alert Manager 1.0.0.0 is very sleek, works only for WSS, but I
couldn't find a tool for SPS, I modified Jan Tielens' code but it worked
only for Top Portal not for areas and sub areas and you must be a super
user. I added my self as a Site Collection Administrator, still didn't work.
Any alert too for SPS, please let me know.

I agree with the Alert Manager from SharePoint Solutions. We installed
this a few weeks back and all our users  love it! Very easy to use and
works as advertised.

I may be wrong about this (going from memory) but I think this Web part
has to be removed from the page after the alerts  are set  for users  to
access the page, or at least without errors as the Web part is an
administrator Web part.

Rather than using a webpart for setting alerts  for
other users  you can have a console application that
does the same.

Classes you will have to use to code it are: -
1) SPPermissionCollection
2) SPPermission
3) SPMember
4) SPUser
5) SPAlert

simply make the application ask you for user name and
then enter theUSerID of the user and your job is done.

Can you share the code with us. I'm tried to modify Jan Tielens' alert web
part code, but it only works if I login as the super administrator of the
box. Maybe I'm doing something wrong.

I would surely send you the code. Right now i am
in Kolkatta so i have no access to it. The application
that i wrote is also for administrators. Infact if you
want to set  alert for other users  only a super admin
can do it or else you have to use impresonation.

Kindly send me the code that you are using riht
now.

I played with this a bit, yep you have to remove the part after you've setup
the alert as even non administrators can alter and add alerts  (despite it
saying you need to be an admin when you log on without admin rights).

Another draw back was that it always sends an alert setup notification mail
too.

I could live with the first one if I could avoid the second one

Well... I simply put this web part in My Personal View... off course u
would'nt want to put it in the shared view... as this web part is only for
administrators.... I don't think u can stop it from sending out notification
emails that an alert has being set  as it rights to the config. Database as
explained on the web site.

Actually, the Alert Manager by SP Solutions sends the email as well. Not
sure if that is something that could be configured or not; for us, the
notification is not an issue.

this is great! but where exactly do i install it????

You have to install it on each front end web.