This is not the most user-friendly of suggestions, but for something simple like this you could just write a small shell script, e.g.

#!/bin/sh

while [ 1 ]
do
sleep 50
#your notification action goes here
dbus-send --print-reply --system --dest=com.nokia.mce /com/nokia/mce/request com.nokia.mce.request.req_vibrator_pattern_activat e string:'PatternChatAndEmail'
sleep 10
#your notification action goes here
dbus-send --print-reply --system --dest=com.nokia.mce /com/nokia/mce/request com.nokia.mce.request.req_vibrator_pattern_activat e string:'PatternChatAndEmail'
done

In this example the phone will vibrate. This might not be a great idea if you use it a lot! If you want a beep you'll have to find a sound sample of the beep first, then substitute the dbus-send lines for an action to play it.

If you want to use this, then save the above as for example interval.sh, making sure to remove the forum introduced space in "/mce/request com.nokia.mce.request.req_vibrator_pattern_activat e", then make it executable by running:

chmod a+x ./interval.sh

To start your training run the script. To end kill it (ctrl-c). If you want to run it from a desktop widget or something you can use the command:

killall interval.sh

to stop it instead.

Cheers,
Jan