Sounds like this thing.
http://www.cfxweb.net/modules.php?name=News&file=article&sid=664
Btw, there is a method based on shears,
12
34
----
12
34 (+x shear)
---
31
42 (+y shear)

and there is variations that rotate by other odd degrees like 22, read a paper once..
use something like a bresenham to ...