Yes.

I preformed an internal monologue with my teacher, and found an certain image that I needed to find in my dreams.
My teacher told me to ask the universe for the dream, quote, "Don't be modest, be forceful and demand the dream.
He then added prayer, saying, "it can super-charge your intent"

I went on and tired it, asking the powers of the universe, and then praying.
Finding success with this, I have recently tried this with lucid dreaming and again, found success.


So to answer your question, Yes I have tired it and Yes it has worked.
I like the use of the term "focused-meditation" as I think it accurately describes prayer in this sense.
I think that prayer can take your intentions from "I think I can" to "I know I can"
and that attitude can be immensely useful when attempting to lucid dream.
Perhaps prayer can root our intention in our subconscious therefor helping us.

( I would like to add that this whole Idea/thread is very synchronistic for me because,
1) The idea of prayer and dreams has been bouncing around my head for some time recently, and
2) What snowkitten describes is synchronicity at its best.
making that synchronicity^2 {squared})