Sony Ericson K750i - how to make it vibrate for alarms? (even in silent mode it makes a sound)

On silent / vibrate mode, it vibrates when people call but it won't
vibrate

I set alarms throughout the day (to help me to remember to take my
medicine pills throughout the day)



So is there a way?

Obviously it's useful for it to make a noise if it's there to wake
you up - vibrating would be no good.