How to practice mindfulness when doing everyday activities - especially intricate and engrossing ones

I'm attempting to bring the Mahasi Sayadaw method of *labeling*, off the meditation cushion, and into my everyday actions. But I'm encountering a few difficulties and contradictions hindering the practice. I've noticed that when I'm doing intricate or engrossing things, such as conversing, studying, working, or playing a musical instrument, it becomes *impossible* to be mindful, or have any awareness (or 3rd-party objectivity) of what I'm doing. If I tried to say "playing", or "lifting index finger" while playing a complicated piano piece, I would lose my place. Or if I'm deep in study or work, entirely engrossed in a subject, I have to discard mindfulness or any 3rd-party objectivity, and just do the work. If I were to say "reading", or "working out the author's thoughts on covalent bonding", I would lose the track, or be forced to come to a dead stop. Indeed, mindfulness seems to *oppose* mastery in action, and I have to discard it anytime an engrossing or intricate action is required. Then inevitably I have to wait until I'm done with the activity, then restore mindfulness when my body and mind can be more stilled. Mahasi suggests that actions should be done in a slow, deliberate way, as though one were physically limited. But I can't see how one could do something as engrossing as playing music, learning a language, or studying molecular biology in this way.