I just did a quick test with Tasker, and it was able to stop the alarm from sounding when the phone was undocked, however the alarm also didn't clear, so it remained set, and I assume would sound again at the appropriate time the following day even though it wasn't set to repeat. I don't know of a way to use Tasker to enable a specific alarm though.
There is also an Alarm Clock profile in the Tasker Wiki that may already do what you want, or may be modifiable to do what you want.