This in your .vimrc will change the cursor movement for Colemak without affecting other vim mappings, because it only affects the h/j/k letters.
- up = h (labelled as "h" on the keyboard)
- down = k (labelled as "n" on the keyboard)
- left = j (labelled as "y" on the keyboard)
- right = l (labelled as "u" on the keyboard)
Here is the mapping:
noremap h k
noremap j h
noremap k j