You can edit /etc/asui-svc to keep ASUI from stopping systemui but it will probably cause duplicate notifications to appear. The power button will also open ASUI and the systemui menu but I think you can keep systemui from opening its menu by changing PowerKeyShortAction from menu to disabled in /etc/mce/mce.ini and then restarting MCE.

Tell me how to create alarms and I'll add support for them as soon as possible.