This doesn't directly address beeping but it can be a possible solution
You might want to checkout this thread: https://developer.motorolasolutions.com/message/8276#8276
In summary, if the user has either the Headset or Speaker accessory for the SB1 you can use the generic.PlayWave API (http://docs.rhomobile.com/rhoelements/generic/) to play a wav file on the scenario you have.
I had seen that thread but our plan is not to have our users carry extra accessories. So that's not an option for us.