Doomie,
Not to beat the point to death, but perhaps the title is too long, or should be split into two lines, with whichever you or your publisher thinks most important appearing at the top in a larger font.
That way, you can keep it as written, one way or the other, and use a preposition or the colon without having a giant spattering of punctuation and a large title.
I also clearly see Bonita's point, and yours. There is no easy way I can think of to reword it, though. While the preposition IN is probably correct, the use of AT seems more prevalent among the books I have seen.