Don't shoot me - but I think a plugin would work wonders for you http://www.adobe.com/cfusion/exchange/index.cfm?event=extensionDetail&extid=1046429
However, you said you can't use a plugin - http://help.adobe.com/en_US/indesign/cs/using/WSa285fff53dea4f8617383751001ea8cb3f-704ba.h tml
Don't shoot me - but I think a plugin would work wonders for you
ImposrPro was a great plugin until Quark bought it 10 years ago.
How do I adjust for creep? I see a setting for it.
The creep amount changes depending on the thickness of the paper—you'll have to experiment. It's automatically adjusted until there's none at the center spread.
So 20pts. looks like this for the cover and back—there's 20 pts between the pages:
And there is none for the center spread:
This is exactly why Adobe strongly recommends against attempting to do booklet-making and other imposition within InDesign itself. This is the domain of high-end imposition software working upon the exported PDF file (logical page order, not spreads) that takes into account the attributes of the specifications of your final “print product” (how it is put together including binding). the print device characteristics, and the dimensions of the physical sheet being printing upon and its thickness.
You shouldn't be committing to such parameters in a layout program which in fact is InDesign other than making sure that your page margins can accommodate worst-case situations.
Print service providers that require that you do imposition are not service providers! They are lazy blame shifters!
I think the OP is printing in house
If the OP has need for this type of sophistication, then he should investigate Acrobat plug-ins that handle imposition if the printer's RIP cannot handle it.