Good to see you here as well.
The SoundBridge firmware does include alarm functionality although it is really only intended to be used on the R1000 radio product. However, it is also accessible on the M1000, M1001 and M2000 products using the appropriate remote control codes - see this thread on a Java remote control app which has been modified to do this (around the fourth page of posts I think).
The issue is that you have the Home Music (a.k.a. M400) and this has a small text display. That application I mentioned works by being able to read back the display to your PC and I don't think it will work with the Home Music product as-is. There may be other remote control applications here that will help you, but you will need to to a bit of searching.
Of course, the best thing would be if Roku could find a way to make this functionality more accessible in the M-series products.