I am interested in obtaining the precise steps which will allow me to
setup an AppleScript which will do the following in FileMakerPro
Server 3.1:

Send a message automatically at hourly intervals to users, warning
them that in 2 minutes the hourly data backup will begin, and so
please stop using the machine until 3 past the hour.

The server machine is an Apple PowerMac 8500/180. The clients are
various PCs running Windows 95/98.

I need to know the setup steps and the actual code.

As of now I'm thinking:

In FilemakerPro Server-->Administer-->Edit Scedules-->Select Run
Script rather than Backup, and select my (yet-to-be-created) script.
Then in the Scedule window, there will be:

9AM warning msg (AppleScript)
9AM backup (Backup)
10AM warning msg (AppleScript)
10AM (Backup)
-->hourly until and incl. 5PM.

As it is now, with no scripts, it automatically backs up hourly, and I
can send messages manually by clicking Send Message, typing a msg and
clicking Send, but I want the warning messages to send themselves
automatically.

Thanks in advance for all assistance!

Omniscientbeing

Do you really need to do hourly backups?  That seems a bit excessive. 
Especially if they make the users stop working for up to 5 minutes
every hour...

Yes, we need hourly backups. Data pertains to medical records for
animals and infastructure is sketchy. Lightning storms are frequent.
I'm not looking for alternative protocols, I'm looking for the exact
solution as outlined in my Question.

Thanks.