Crawl uses the vi keys for movement, so yubn are your diagonals. You can also use a numpad if you've got one (you probably don't on a laptop though). There's also mouse navigation, clicking where you want to go.
- Code:
keyboard movement options
y k u 7 8 9 ↑
h 5 l 4 5 6 ← →
b j n 1 2 3 ↓
You cannot push multiple keyboard keys to produce a diagonal the way video game directional pads work (...though if you have a d-pad controller for your computer, I suppose you might be able to map it's inputs to crawl). Shift + direction runs instead of moving a single square.