Diagonal connection between nodes?

I have four nodes arranged in a square like so:

 .---.   .---.
| CTR +-+ WBK |
 '-+-'   '-+-'
   |       |
 .-+-.   .-+-.
| HWD +-+ SDO |
 '---'   '---'

I'd like to diagonally connect the HWD and WBK nodes from their nearest corners, but haven't found a good solution. Most come out mishapen or connect the sides of the nodes rather than their corners. Any ideas? The horizontal and vertical space between nodes can be increased if that makes it any easier.