I pinned the scarf to my blocking board (a dress making board, that has a wonderful grid at one inch spaces), and spritzed it with some water.
Before spritzing, I evened it out along the board, and was able to do half the scarf at a go.
The blocking made the cables really pop, and while it didn't stretch out as wide as I thought it would, it did look a lot better after I'd blocked it.
I mailed it off to Lyle, and I hope he will send me a picture of himself wearing it. If he does, I'll post it here!