[R] passing par() options to pdf under Sweave

[Anne York]

I'm using Sweave to generate LaTeX output from R. Thank-you 
very much for this capability. It is very useful.

Could someone please tell me how to pass non-default 
graphics parameters from par() to the pdf driver when it is 
called by Sweave? 

(I need to change some of the margin defaults. )

Hoping there is an easy solution to this question,

Anne York