You'd need something boring. Like a lecture; but a dry, dull, lecture, that most definitely does not capture you...
...because for some odd reason we daydream while not paying attention, not when spacing out.

And daydreams. How they transport, transfer, you from any sense of reality, is, in essence, magical.

Now to exploit them for Lucid Dreaming
As I said, you'll need boredom. And then you'll need imagination. So, at night, you know that moment when you snap out of a daydream? I suggest you do a reality check. Then, if it fails, too bad. Try again, maybe with something more boring. But if it succeeds,

So I suggest maybe four or five sources of potential boredom, each varying in depth of attention-loss.

Come to think of it, here's an example, possibly analogous to sleep paralysis. The way I see (perhaps feel is more adequate here) SP is not the inability of movement, but the utter lack of any will-power to move whatsoever. This reminds me of when you stare at a window, or picture, and your mind races. You become so fixated with your object, you can't look away. After this, you should, too, do an RC.

Sum it up:
Stare at something captivating.
Get captivated.
--RC--
Get something boring.
Get bored.
Continue 'reading' or 'listening to' said boredom-source...
...while actually getting in a daydream.
(You might fall asleep here)
Snap out of daydream.
--RC--

Lather, rinse and repeat.

That'll be all