I've recently (on and off for the last couple of years) tried writing music for my words, and turning them in to songs. I, too, am more verbal than musical in my thinking, and am driven most by the story, or idea I want to get across.

The technique that works best for me is to say the line out loud, as if I were speaking it to someone I care deeply about, or someone I want to convince of something, and listen to the rise and fall of my voice as I say those phrases. Then, I simply "exaggerate" those differences into the varying pitches and rhythms of a melody.

I really recommend a program called Noteworthy Composer -- that lets you set up a staff, stick notes on it, and play it back. If it doesn't sound right, you can tweak it. You can download a free, nearly 100% enabled version for a month of shareware to try it out. You can get to their page by clicking here (and no, I do not get a commission by posting this -- honest!). Even if you never buy it, the thirty days would probably give you enough of a experiment with putting tunes to your words....