Spent hours of time and lots of paper trying to print a custom size.
Guess I should have came to the forum sooner!
For what it's worth my system is: Mac OSX 10.4.11 (Tiger)
I will try the work around as described above and edit this post with results.
 Nah, I give up, too much waste of time. Guess I will have to purchase a supported plotter or go back to pencil and ruler.