If you punch a hole in the corner it'll hang aslant, but if you punch a hole in the top centre it'll dangle straight down.
From the guardian.co.uk
But the image itself is taken at a slight angle that notably runs aslant of the plane of the stairs, which is slightly disarming.
From the learning.blogs.nytimes.com
Slowly, the world settled back into some semblance of order, the porch boards still warped, the chimney still aslant, but all the pieces more or less fitted together.
From the charlotteobserver.com
The sofa had curlicues of moss-colored velvet running all over its sage-green hide, and it was so deflated and aslant that Burr swore he only ever kissed me the first time because of it.
From the denverpost.com
The carts were joined wheel to wheel by chains and positioned aslant, with their corners attached to each other, so that horses could be harnessed to them quickly, if necessary.
From the en.wikipedia.org
More examples
Over or across in a slanting direction
Having an oblique or slanted direction
Obliquely: at an oblique angle; "the sun shone aslant into his face"