I should not I would like the booklet to have 2 pages per sheet and fold in landscape orientation.
I can recomment not to use the booklet. Let the printer do the imposing.
When I go into print settings I am unable to play with the size and orientation.
If you are doing the printing in-house you need the Adobe PDF 9.0.
Read the instructions on the above page carefully. You have to control-click the Acrobat 9 PPD link under Install Adobe Acrobat PPD and choose Save Link As (don't click it). And then pay attention to #3 in the instructions
With the PPD you can choose a custom dimension, which can be anything: