How to set default printer's page length?

[baash05]

I need to print a pdf so I shell it to the adobe on my system. (seemed easiest). Problem is that when I shell a legal sized doc and my systems printer is set to do leter it adjusts the image and prints it at around 75% of normal so the image fits on the paper..
This is not acceptable.
I am therefore trying to set the default system printer to print at legal size.
I'll set it back when I'm done.

Any suggestions would be helpfull.