Use mantras as you are falling asleep and throughout the day at random intervals. Maybe only do a repetition cycle of mantras (just repeat it a bunch of times, paying attention to the intention of the mantra) once during the day, and then as you are falling asleep to make it the last thought you have before you sleep.

As for setting an alarm, you can either choose not to as others have said, or you can use your REM cycles to set one. They happen at the end of every 90 minute sleep cycle, and grow longer the longer you sleep. I would recommend setting one 4.5-6 hours after sleeping. It will take some experimentation to find the correct timing to wake yourself up, since everybody is different, but when you do it will be a lot easier